Trying to use the HTTP OAuth2 request to connect with my ebay Developer to make secure API requests

I am looking for help from someone who has been able to make HTTP OAuth2 requests to ebay using their developer account.

I was able to successfully obtain the Client ID and the Client secret but I am confused where I can find the Authorize URI and Token URI from ebay. From my understanding they use something called a RUName instead. But when I’ve tried to use this I am not able to connect. I get a popup that says the connection worked with ebay but not with the app.

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