Hello @Kim Strasser ,
You can right-click your iOS project, go to Properties -> Build->iOS Bundle Signing, then select Developer (Automatic) for Signing Identity and the corresponding provisioning profile. If there is not a valid profile, you can go to Preference->Publishing->Apple Developer Accounts, select your account and view details, then download the profile. If there is still not a valid profile, you have to create a new one, see Manual provisioning for Xamarin.iOS - Xamarin | Microsoft Learn
A paid Apple Developer account is required to use this feature. If your account is Individual, please go to App Store Connect, click User and Access, go to Keys tab, choose App Store Connect API, then generate an API Key, and enter the information in VS (Preference->Publishing->Apple Developer Accounts->Add->Individual Account). For more details, you can refer to Apple Developer Documentation - Creating API Keys for App Store Connect API
If it is Enterprise, you can add this account directly.
If you do not have a paid Apple developer account and you are using a free provisioning for Xamarin.iOS apps, the Bundle Identifier in the Xamarin.iOS project and the Xcode project should be the same, because Xcode will only create a provisioning profile for an explicit App ID.
(Note: If you cannot see your signing identity or the correct provisioning profile, you may need to restart Visual Studio for Mac.)
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