That “Not eligible to advertise” message typically means one of two things is going on—both are common after connecting a fresh Instagram account to Meta Business Manager.
Most Common Causes:
1. Instagram Account Isn’t Fully Set Up
It might still be a personal or creator account. For ads, it needs to be a business account.
Fix: On Instagram, go to Settings > Account > Switch to Professional Account, then choose Business.
2. Instagram Is Not Properly Connected to the Facebook Page
Even if it's added to Business Manager, the Instagram account must be connected to your client’s linked Facebook Page.
Fix:
Go to the Facebook Page > Settings > Linked Accounts.
Reconnect the Instagram account there.
Make sure the correct permissions are granted during the connection process.
Bonus Checks:
Ensure you’re using Meta Business Suite or Ads Manager, not just Boosted Posts.
Double-check that the Facebook Page and Instagram are owned by the same Business Manager.