Re: App Store rejects my password
Your Apple Account is the account you use to access Apple services like the App Store, Apple Music, iCloud, iMessage, FaceTime, and more. It includes the email address and password you use to sign in as well as the contact, payment, and security details you use across Apple services.
Seems the App Store requires your Apple Account password you use to log-in to your account, rather than the Mac log-in you tried to use.
You can check you are signed in to your iPhone with your Apple Account ID and password:
Sign in to your Apple Account on the web or in your device settings - Apple Support
What to do: If you forgot your Apple Account password - Apple Support
and / or
If you forgot your Apple Account primary email address or phone number - Apple Support
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If more help is needed: Check if any restrictions are set:
Manage App Store purchases, settings, and restrictions on iPhone - Apple Support
and / or
You can check whether your iOS version is up-to-date in Settings > General > Software Updates
(Please remember to back up iPhone data first, if you decide to update the iOS version.)