When you try to add your Facebook Page to your Business Manager and see “Request sent,” it typically means the Page is already owned by another Business Manager—even if you’re unaware of it.
The request is being sent to the current Business Manager that has ownership of the Page, and unless they approve it, you won’t gain access. To check, go to your Facebook Page settings → Page Access → Business Account Access and see which Business Manager is listed.
If you recognize it, you’ll need to contact that admin to approve or transfer access. If not, you can file a Business Asset Ownership Dispute with Meta by providing documentation proving ownership of the business or Page. Avoid sending multiple requests, as it can trigger security reviews.