i got diamond premium and cant get badge
It looks like you should be getting it. Are you on a free trial? Maybe you have to actually pay.
Yes, Martin Stahl says that you have to pay and get off the trial to get the achievement.
https://www.chess.com/forum/view/help-support/not-getting-chess-com-supporter-award?page=2#comment-84514865
👆 If you're still in the trial you won't get it until it converts to a paid membership.
i got diamond premium and cant get badge