As i understand it, you need Paypal Pro (a paid upgrade, maybe subscription?) to have the transactions done on your page, rather than the transaction on the Paypal page. Afaik Cart 2 will only work with Paypal Express, and I believe all the Paypal stack options use Paypal Express. @yuzool Michael has mentioned this another thread. Maybe I can find it.
I’ve read here on the Forum that Stripe lets you have the checkout on your own page.
[edit - found the thread:]
Apparently this was in answer to your post: