To log into your Rec Room account, recover your password, manage your email / notifications / custom room settings, please visit Rec.Net
How to find your username
You can find your username through your watch menu in-game.
Open your watch, navigate to your profile (top left on home menu)
You will find your display name and your username near the top of the profile tab.
Keep in mind that your username is not the same as your display name, all usernames are unique and cannot be changed. Your username will always start with "@".