Macbook Pro will not sync all photos in Icloud library

Hello mmoore0405,

Welcome to Apple Support Communities. 

We understand that you don’t have access all of your photos until you update your Mac. We are happy to help.

Please use the steps here to update your Mac: Update macOS on Mac - Apple Support

"Use Software Update

Before installing new software, it's a good idea to back up your Mac.

1. From the Apple menu  in the corner of your screen:

• Choose System Settings. Then click General in the sidebar, and Software Update on the right.
• Or choose System Preferences. Then click Software Update.

2. If Software Update finds new software, click the Update Now or Upgrade Now button to install it.

3. Enter your administrator password, if asked. During installation, your Mac might restart, and you might see a progress bar or blank screen several times.

If Software Update says that your Mac is up to date, then no new software is currently available for your Mac model. Software Update shows only updates and upgrades that are compatible with your Mac.

If you don't see Software Update

If you don't see an item named Software Update in System Settings or System Preferences:

• Use Search in the corner of the window to search for it.
• If your older Mac doesn't include Software Update, open the App Store app, which is in your Applications folder. Then click the Updates tab in the App Store to check for updates. You can also search for software by name."

Let us know if you have further questions.

Take care.

mmoore0405 Said:

"Macbook Pro will not sync all photos in Icloud library. I see this error"

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Thank you for the screenshot.

Updating the macOS:

Determining which Update(s) will Install:

I. Verify Compatibility:

A. Start Here: Learn About Compatibility and how to Identify your Specific Mac Model - Apple Support

B. How to Verify:

I Reveal your Model:

What is the Model of your Mac? To find out...

1. Go to: Apple menu
2. Click: About this Mac
3. View: Second Line-Down

then...

II. Compare the Results:

See if the Model you found is shown here:

• macOS Ventura is Compatible with these Computers - Apple Support

III. If Compatible:

Back Up your Mac First:  Be certain you Create a Time Machine Backup of your Mac, so that way you can have something to restore your Mac from, should anything go wrong with the reconfiguration.

This message suggests that you enabled Shared Photo Library on another device (perhaps an iPhone or an iPad) connected to the same Apple ID, but your Mac is running a version of Photos too old to be able to see the contents of the Shared Photo Library. The 301 photos and 29 videos should match your donation to the Shared Photo Library.

Ron_H1 noted how to update your Mac if it is capable of running Ventura. If it is not capable of running Ventura, or if you choose not to update your Mac to Ventura, your choices are to stop using Shared Photo Library (reclaiming the photos and videos back into your private library) or to live with the message (and inability to access those items).