Account Sign Up Failure with github and discord - and a bad link

When attempting to sign up for a forum account using the github link. The site redirects to a certificate warning. “Websites prove their identity via certificates. Firefox does not trust this site because it uses a certificate that is not valid for forums.codaprotocol.com. The certificate is only valid for *.discourse.org.” If you accept the risk you are taken to https://forums.codaprotocol.com/auth/github/callback?error=redirect_uri_mismatch&error_description=The+redirect_uri+MUST+match+the+registered+callback+URL+for+this+application.&error_uri=https%3A%2F%2Fdocs.github.com%2Fapps%2Fmanaging-oauth-apps%2Ftroubleshooting-authorization-request-errors%2F%23redirect-uri-mismatch&state=8b5a3dbfb4f1e5208c577d5bafe3fb0aee5dff46b37299c2 where it states the site does not exist under a big Discourse image.

When attempting to sign up for a forum account using discord. I receive
“Invalid OAuth2 redirect_uri”

The only way to sign up is to use the email sign up.

Also the link for “contact us” on the bottom of the about page “im only allowed 2 links”

it gives this message. I found this when trying to find help for the sign up issues " Oops! That page doesn’t exist or is private."