Please complete all steps at the link in 1. SETUP (REQUIRED).
In summary for Facebook:
Invite Yev/Zontracker as admin (not as employee) to your Facebook Business Manager. Zontracker's team will activate the FB settings (0 - 4 days). After this step you will see the new column in FB Ad Manager for Amazon purchases.
Make sure you invited us through the Users or People section of Business Settings https://business.facebook.com/settings/people/
Access level is not sufficient if invited from Accounts/Ad Accounts or as employee.
ADVANCED ONLY: Please contact support to request alternative signup process (Does not require Zontracker to access your FB account. More steps for you. Harder for us to provide support if you can't figure it out.).