In WordPress 5.5 the feature that was requested 11 years earlier was finally implemented: The ability to update plugins from a .zip file. If you use an earlier WP version you need to delete the plugin you want to upload before you install another version.
And this is how you install a new plugin or new plugin version from .zip. You can also watch this video howto .
- Go to your WordPress Admin Area ⇾ Plugins ⇾ Add New.
- Click on Upload Plugin at the top, choose the .zip file you downloaded earlier and install it, after install click activate.