Hi there, sammyjam97.
It sounds like you are someone's Legacy Contact, but you can't save the access key.
How to add a Legacy Contact for your Apple ID - Apple Support -- We noticed you came to Apple Support Communities from this article, but we wanted to point this out:
- "If your Legacy Contact is using a device with iOS 15.2, iPadOS 15.2, or macOS Monterey 12.1 or later, you can notify them via Messages when you add them, and if they accept, they automatically store a copy of the access key in their Apple ID settings. You’ll receive a notification if they decline your Legacy Contact request, and you can choose someone else."
The access key should automatically be stored on your iPhone. To confirm, you aren't seeing the "View Access Key" option in Settings > tap your name > Password & Security > Legacy Contact > tap the contact you are a Legacy Contact for.
If you aren't seeing the access key there, you could see if restarting your iPhone may help: Restart your iPhone - Apple Support It refreshes the iOS and could possibly help with this issue.
Take care.