Hello,
Thank you for reaching out to us. We apologize for the inconvenience you’re experiencing with the Content AI credits.
If you are on a free account, you should have received a 30-day free trial of the Starter plan for Content AI. To refresh the credits, please navigate to your WordPress Dashboard → Rank Math → General Settings → Content AI and refresh the credits. Here’s a screenshot for reference:

After refreshing the credits, you should be able to generate content using Content AI without any issues.
If you are still facing issues after refreshing the credits, please let us know, and we will be happy to assist you further.
We appreciate your understanding and patience as we work to resolve this issue for you.
Sources:
How to Restore Missing Content AI Credits » Rank Math
I did refresh severally but no credit was generated; rather, a pop-up showed in my browser when I clicked on the refresh, saying MY SITE IS BLOCKED, CONTACT SUPPORT, what should I do about that?
Yes, I am refreshing it from my WordPress dashboard and it keeps popping up that warning “YOUR WEBSITE IS BLOCKED, CONTACT SUPPORT”.
Even now, I tried it again, but got the same error, it can not get any credit
Hello,
Thank you for contacting us and sorry for any inconvenience that might have been caused due to that.
Unfortunately, we are not able to see any Content AI subscription on your account. Can you please confirm if you purchased the Content AI subscription with some other email address?
If so, please share the email address that you used to purchase the subscription or you can search and forward the receipt from FastSpring.com so we can locate your account and check the issue.
Looking forward to helping you.
Thank you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.