Installation

To install an addon in blender you must follow the following steps:

1 Go to Edit > Preferences..

2 Addons section 

And click on the button above that says Install...

Then a new window appears in which you must search for your downloaded .zip file.

You select it and give to the button that puts Install-Addon.

Usage

Select your objects and click in Add Wireframes.

If you use Eevee and transparency, I recommend you to increase the samples, or change the Blend Mode to Alpha Clip. By default it is Alpha hashed, because it works best in all situations, but the disadvantage is that you have to increase the samples for Eevee.