Having trouble enabling Apple's iCloud Advanced Data Protection? Is it that you keep getting inexplicable errors or silent fails when you try? I've done some troubleshooting and found several distinct errors and their fixes, and blogged about it here: https://www.tarah.org/2023/01/27/troubleshooting-apples-icloud-advanced-data-protection/
Troubleshooting Apple’s iCloud Advanced Data Protection – Tarah Wheeler

@Tarah Nice! My approach was more brute force, didn’t work on my Mac. Tried on my iPhone and it worked. I did not set recovery contact, only recovery key.