In the Zoom desktop app, you can click on your account in the upper-right and select "Check for updates" to see if you are up to date or if there is an update available.
To set Zoom to install updates automatically when you log in:
Click on your account in the upper-right.
Select "Settings", and the "General" page is shown by default.
On this page, under "Zoom Updates", check the box for "Automatically keep Zoom desktop client up to date".
Detailed info:
Zoom has a required "minimum version" of the app, and this gets revised periodically during the year.
If you have an outdated version of the app, you may see an "update required" message when you try to login, and you may be logged out of your Zoom Client, or not able to join meetings via the Zoom Client until you update.
For more information on minimum version requirements click here.