Subdomain/payment processing - Can't find Stripe related forms

[murkojxm]

Problem: Where is the payment processing related content/forms located?
Background: I'm a professional software engineer with many years of experience, but fairly new to Joomla.
I got access to an existing and working website that I was asked to modify.
Modifying the content, adding/removing images and articles was fairly simple.
But I went to the whole website, I red help and googled for this, and I can't figure out WHERE is the content for the STRIPE payment and related forms hosted.
I see on the Networking Tools of the browser that this missing content is coming from a subdomain called pay.
Is it possible it is configured in a completely different instance (of joomla or something else)?
There are 4 forms you go through when you pay, but I don't see any of these forms.
I found out there are different extensions for forms and payments and subdomains, but none matching this site.
Also one of the articles has content of {laodmodule mod_articles_news, module1}, but when I go to Modules - module1 - there is no content, just configuration.
Any ideas?
Site info: This site has not been touched since 2018. It runs on Joomla 3.9.1, PHP 7.2, MySQL 5.7.
I was not asked (and not being paid) to upgrade anything, but it might help with narrowing down the options for a fairly old system.
The owner has no technical background, he bought the business related to this so he does not know who did what, and I talk with a no technical manager. So no help there.
Thanks.

[gws]

Payment options are often plugins, have a look in plugins.

[Webdongle]

There are several STRIPE payment gateways in Joomla's extension directory. Some integrate with Virtuemart shopping cart. The location for editing may be in the shopping cart used. Being professional software engineer with many years of experience you will know that STRIPE is a payment gateway and shopping cart software connects to that gateway.

With Joomla the shopping cart software comes in the form of a Component (that has Modules and Plugins). The shopping cart connects to the payment gateway with a plugin. Sometimes that plugin is with the shopping cart Component other times it's a separate extension.

Depending on what you want to achieve you might need to look in the shopping cart Component. By looking in the shopping cart Component you can see (or change which payment gateway to use. Credentials for the payment gateway can be found either in the shopping cart Component or the plugin.

If you run the fpa https://forumpostassistant.github.io/docs/ and post the results here then someone might recognise the Component/plugin.

Also if you do a web search for the shopping cart Component and the plugin
site:https://extensions.joomla.org/ extension name
Then you should find a link to documentation on the Joomla extension

(it might help to think of plugins as sub routines?)

[murkojxm]

Thanks, gws. Here is the list of all plugins ordered by type.
Do you see any suspects here?
thx.

Plugin Name Type Element
Action Log - Joomla actionlog joomla
Action Log - Visforms actionlog visforms
Authentication - Cookie authentication cookie
Authentication - Joomla authentication joomla
Content - Contact content contact
Content - Email Cloaking content emailcloak
Content - Fields content fields
Content - Joomla content joomla
Content - Load Modules content loadmodule
Content - Page Break content pagebreak
Content - Page Navigation content pagenavigation
Editor - CodeMirror editors codemirror
Editor - None editors none
Editor - TinyMCE editors tinymce
Button - Article editors-xtd article
Button - Contact editors-xtd contact
Button - Field editors-xtd fields
Button - Image editors-xtd image
Button - Menu editors-xtd menu
Button - Module editors-xtd module
Button - Page Break editors-xtd pagebreak
Button - Readmore editors-xtd readmore
Button - Visformfields editors-xtd visformfields
Extension - Joomla extension joomla
Fields - Calendar fields calendar
Fields - Checkboxes fields checkboxes
Fields - Colour fields color
Fields - Editor fields editor
Fields - Imagelist fields imagelist
Fields - Integer fields integer
Fields - List fields list
Fields - Media fields media
Fields - Radio fields radio
Fields - Repeatable fields repeatable
Fields - SQL fields sql
Fields - Text fields text
Fields - Textarea fields textarea
Fields - URL fields url
Fields - User fields user
Fields - Usergrouplist fields usergrouplist
Smart Search - Categories finder categories
Smart Search - Contacts finder contacts
Smart Search - Content finder content
Smart Search - News Feeds finder newsfeeds
Smart Search - Tags finder tags
Installer - Install from Folder installer folderinstaller
Installer - Install from Upload installer packageinstaller
Installer - Install from URL installer urlinstaller
OSMap - Joomla Content osmap joomla
Privacy - Action Logs privacy actionlogs
Privacy - Consents privacy consents
Privacy - Contacts privacy contact
Privacy - Content privacy content
Privacy - User Messages privacy message
Privacy - User Accounts privacy user
Privacy - Visforms privacy visforms
Quick Icon - Akeeba Backup Notification quickicon akeebabackup
Quick Icon - Joomla! Extensions Updates Notification quickicon extensionupdate
Quick Icon - Joomla! Update Notification quickicon joomlaupdate
Quick Icon - PHP Version Check quickicon phpversioncheck
Quick Icon - Joomla! Privacy Requests Notification quickicon privacycheck
Sample Data - Blog sampledata blog
Search - Categories search categories
Search - Contacts search contacts
Search - Content search content
Search - News Feeds search newsfeeds
Search - Tags search tags
System - Debug system debug
System - Fields system fields
System - Highlight system highlight
System - Joomla Options system joomla_options
System - Language Filter system languagefilter
System - User Log system log
System - Logout system logout
System - Log Rotation system logrotation
System - Joomlashack System Plugin system ossystem
System - Remember Me system remember
System - SEF system sef
System - Session Data Purge system sessiongc
System - Joomla! Statistics system stats
System - Joomla! Update Notification system updatenotification
User - Joomla! user joomla
Visforms Spambotcheck visforms spambotcheck
Visforms - Visforms visforms visforms

[Webdongle]

Please run the fpa and post the results. It will give a full list of components, modules as well as plugins. And their versions.

[gws]

As webdongle as said please run the FPA (see red box at the top of the forum) read the docs first. It will help us help you.