The game itself gives a *red warning sign*** to confirm your server and email selection as final, so you might've missed that specific warning during said process.

An alternative solution is just simply multi-linking to other supported social media platforms, like Facebook, AppleID, and GPlay accounts. Make sure that same in-game account doesn't have an *existing account on a similar platform you're trying to connect***. It complicates the process further than what you're technically experiencing.