There are a few possible reasons causing this issue:
1. You have entered the wrong email address.
2. You are in a different Stella build (Standard/Next/Staging.v2)
3. You are logged into another Stella Account when you click the verification link.
4. Your email verification link is expired. You need to verify your email within 24 hours. Please resend and try again.
Please see the related documentation here and verify your email here.