How to activate my account on Adobe Stock?

There is nothing you CAN do but wait. At least they replied and let you know that they will keep you up to date with their results.

Using the e-mail address is the less preferred method, because e-mails are not guaranteed to reach the destination.

If your account has been suspended, there is nothing that this community of peers can do for you. You will need to contact Adobe contributor support via the link at “Contact us”. Adobe will answer via e-mail, so watch your spam folder. The answer may take some time, depending on the workload of contributor support and the complexity of the investigation. So be patient and do not spam the contributor support.

Adobe may temporarily suspend or permanently terminate a Stock Contributor account for any of the following:
1) Suspicious sales or refund activity,
2) They received an official infringement complaint or "take down" notice from a 3rd party,
3) Suspected violation of Stock Contributor User Terms,

If you don't hear anything within 15 business days (check your spam folder for reply), send a follow-up inquiry. Do not spam the system with tickets.  Be patient.  Meanwhile work on other projects.  You may submit work to other microstock services if you wish.