There's usually nothing you can do. It's not like you did anything wrong; your game simply needs to wait for a manual review by the staff. Although the documentation says it takes a few days, in reality, it usually takes the staff a couple of weeks to complete these reviews.
The most common recommendations are not to rely on being indexed and to handle all the promotion yourself.
If you think there's an error, you should try contacting support (this forum is answered by the community, not the staff). You can copy the ticket number you receive in your email here and politely ask the moderator if they can notify the staff about your ticket.
Also, keep in mind that Itch doesn't index all games. The documentation doesn't mention this, but I've seen several games go months without being indexed, and the exact reason why is unknown. In the few cases where the admin has given an explanation, it is usually because there was a problem, for example, a copyright claim, or people who spammed.