@Thi6 - Experiences are a pretty unique and specific thing. Airbnb needs to take a lot of liability for the activities they provide on their website. It's not as easy as posting a listing. It must be vetted and approved by Airbnb. The forums are mostly manned by other hosts, so we cannot really give you any insight on "how to do next". You have to wait on Airbnb to approve or deny your Experience proposal.
The message says they will get back to you in 7 Business days... so not just 7 days. If you still don't hear from them, make sure you are checking your email too, then I would suggest contacting them.