Zoom periodically updates it's "client," or the little app you have on your phone or PC that allows you to attend meetings. The app may at some point automatically update, but this may be inconvenient if you are trying to promptly join a meeting. You can update this app manually, and is worth doing since Zoom's updates frequently contain security enhancements.
Within the Zoom app, click your account icon in the upper right, and from the dropdown menu, choose "check for updates." Zoom will check to see if an updated version of the app is available, and will update accordingly.
If for some reason this update process doesn't work properly, you can always return to Zoom and reinstall the latest version.