Hello MrENG.
Thank you for using Apple Support Communities. Sounds like you're getting invited to be an account recovery contact but when trying to accept the invite, it doesn't take you to the page to accept. If so, we'd like to help out. First, we need to make sure that you meed the requirements to be a recovery contact. If you don't meet these requirements, you can't be an account recovery contact: Set up an account recovery contact - Apple Support
Your device must be running iOS 15, iPadOS 15, or macOS Monterey or later.
You must be over the age of 13.
You need two-factor authentication turned on for your Apple ID.
You need a passcode set up on your device.
If everything is correctly set up on your end, try restarting your device to help refresh things: Restart your iPhone - Apple Support
We hope this information is helpful. Cheers.