Invalid authorization code for custom social connection OAuth

I am pretty new to using Auth0 and have been working on setting up a custom social connection through Square. However, whenever I try to test the social connection, I get:

   "statusCode": 403,
   "data": "{\"error\":\"invalid_grant\",\"error_description\":\"Invalid authorization code\"}"

Through the logs, there appears to be a successful login but a failed exchange due to invalid authorization code of type “feacft”. I’m unsure what the login flow is like through Auth0, as testing the Square APIs manually works.