Myuplink, invalid request

I should have everything done according to https://www.home-assistant.io/integrations/myuplink

Application credentials pointing to the myuplink integration added using the credentials from myuplink application I created. I think it might have something to do with the callback url but can’t figure out what.

I used the external url for HA, https://xx.xxxxxxxx.com/auth/external/callback

myUplink integration has a configuration step that I guess authenticates the integration, that step returns a " Sorry, there was an error : invalid_request"

Since myuplink links to an external web page that in turn can’t handle the request, nothing shows up in the logs.

Any ideas what I might be missing?