Social Logins enable your users to authenticate with another account they already have somewhere else (e.g. their Google account).
Qloud enables all social login providers with its own registered client apps by default. This is great for testing, but you should register and configure your own applications with each login provider you plan to integrate before you go to production.
We have put together guides on how to do that for each provider.
The pre-configured social logins are incompatible with custom domains. Therefore, they are automatically disabled when a custom domain is configured.