HELP! Mac keeps saying update Apple ID settings.. Also calendar doesn't sync.

If you plan on continuing to use your computer to the fullest, you have do as requested.

If you want to keep copies locally then respond to do so.

All synchronizations are accomplished via your Apple ID. And all devices need to be on the same ID with updates applied and entries made to keep all things current.

You can set up iCloud Photos so that when your Mac or iPhone is low on storage space, it will automatically delete full-size local copies of some of your photos in favor of space-saving versions. (Later, you can download full-size versions from iCloud, on demand.)

Set up and use iCloud Photos - Apple Support

But even with that option selected, your Mac may try to pull-down as many full-size copies as possible.

They're just files. Decide what folders you want to keep, maybe put them all on an external drive for security, and move forward.

You can always delete the duplicates created and copy back the data on the external drive.

At least you'll know and then you can decide exactly what to keep.

You have to make up your mind you have an "out". If I guess and it doesn't go as planned, them I'm at fault .... you decide.

"Hi - deciding what to keep when signing out is not an available option - either keep or don't keep."

How can that be? You're at a juncture, and you have to go one way or the other ... or stagnate.

But, Good luck!

That's odd. Apple thought he did and recommended his response.