Might try restarting your browser? And what browser are you using? I have had no trouble on my end. Be sure you type your name in properly and that it resolves your avatar; then the button should become clickable.
delete the last letter in their username, then re-enter it again. you must do so untill their characther face picture shows up, then itll work.
It sometimes does not load it when you have entered the name.
Maybe a force buy.
If it glitches on our end, with a confirmation window that we are sure we have entered the username correct
It would only pop up if the face is not loaded in.