So I installed the plugin and setup my client id/secret etc for my own hosted gitlab instance (added system oauth applicaton in /admin/applications). It redirects me to the main wordpress page with a “/?code=somethingsomething” URL after authenticating in gitlab but only shows: “No request found for this application.” wp_debug is on but I don’t see any more errors.
Ah just tested the github app and that one works. Even public gitlab will give the same error if you select gitlab when selecting. So it’s not a configuration error on my site. The custom one works, but for a plugin that charges 300$ for the cheapest option you would expect every preconfig to work.