In
Settings → Integrations, connect a revenue source:
App Store Connect (installs + revenue by campaign token),
Superwall (real-time subscription events), or
Shopify / Stripe for a store. This is what lets a sale trace back to a post.
For an iOS app you can skip all of them: the
iOS SDK reports purchases straight from Apple, with nothing to set up on Apple's side and no other service in the middle.