update for logic Pro X ?

OK. Try this:

Logout from the Mac App Store.

Quit (Command-Q) Logic and App Store app.

Restart the computer.

Open the App Store App and login to the Mac App Store.

Any changes?

Also ensure you don't use any third party applications like an Antivirus or a Firewall.

it just spins

This is usually the sign that macOS or the App Store app is waiting for user input. The dialog maybe masked or blocked.

WD

Are you using Mac OS Mojave or Catalina? Those are the minimum for 10.5

Because it may take some time depending of your location and other factors. If you navigate directly to the Logic page on the Mac App Store you can click on Update.

WD