Installation¶
Go to Edit>Preferences>Get Extensions>Install from Disk (target the directory where you have the .zip addon file).

How to Properly Update the Addon¶
To update the addon, there are a few steps required necessarily
Remove the old version of the addon
Install the latest version
Restart Blender and it will be updated
Warning
It is important to remove the older addon version before updating, as many errors and bug reports will happen because of an incorrect update method.
If you constantly install the newer addon version directly, the old files will not be replaced.
While not often, restarting Blender after an addon update is required for the addon to work properly.