redirect to app using an external payment service

Question

I have created a dot net maui app. I'm using an external payment service called payfast.

When I want to make a transaction it directs me to a different page on the browser where I make my transactions. When the transactions are complete, I need to redirect back to the maui app.

The issue is that the service does not allow maui's url for example "myapp://". I get an error 400 bad request. "return_url: The return url format is invalid"

I tried to let it redirect to my API which is successful, but then I can't redirect the API back to my app

I have tried both return RedirectToPage("myapp://") and Request.HttpContext.Response.Redirect("myapp://") but it does not redirect back to my app