Link App Store Connect accounts
If you want to promote an app with Apple Search Ads, you must link to an App Store Connect account
You can link App Store Connect accounts to Apple Search Ads when you first create your account or when you create new campaign groups. If you have multiple App Store Connect accounts, you can link each one to your Apple Search Ads account to promote the associated apps. Or, if you have an agency account, you can create separate campaign groups for your clients and link them to each client’s App Store Connect account.
Linking your App Store Connect account to your Apple Search Ads Advanced account lets you promote apps to the additional customer types “Returning users” and “Users of my other apps.” If you don’t link to an App Store Connect account, you won’t be able to promote an app with Apple Search Ads.
Note that the App Store Connect Legal Account Holder, App Manager, Admin, or Marketer must hold either the Account Admin or Campaign Group Manager role to link the App Store Connect account to Apple Search Ads.