As Richard mentioned, the documentation is for DotNet only. I looked at their videos and they look like DotNet only too. A couple of thoughts:
1. Here is the github repo for their library: GitHub - stripe/stripe-dotnet: Stripe.net is a sync/async .NET 4.6.1+ client, and a portable class library for stripe.com.
] you can look at those helper methods to see what they are doing. DotNet uses DI, but you should be able to make your own implementation.
2. Raise a support ticket. I am certain that you are not the only one with this question and they should have a canned support solution that they can respond with.
3. Maybe it is time to move to DotNet - your website will perform better. Here is documentation on migrating: Port from .NET Framework to .NET 6 - .NET Core | Microsoft Learn