Social sign-in only works for an existing account with that connection. It does not silently create a new account. A provider can also return a different email or identity from the one you used when creating your Polymorfa account.
Try a sign-in method already linked to the intended account. If you are a new customer, complete sign-up rather than repeating sign-in. If you expected an existing connection, tell support which provider and account email you used, along with the visible error. Do not send the provider's access token or private callback URL. A second account will not inherit the first account's team access.