Their self-exclusion rules state that you need to email support@coins.game and tell them for how long you want to be excluded. So do that.
The screenshot you posted says that if the self-exclusion isn't completed in time, you will have to restart it. That means, you can't go back and click on the old link and expect it to work. You need to do the same steps that lead to you receiving the information in the self-exclusion email.

Let me ask you something and try to answer honestly if you can. If and when you get excluded from Coins.Game, will you stop gambling forever?