1. Extract archive contents to /Skins folder of Rainmeter
1.1. Expected resulting configuration ini file location: C:\Rainmeter\Skins\<config_name>.ini
2. Launch Rainmeter
3. Locate Rainmeter tray icon and make a right click on it
4. Navigate via pop-up menu to newly installed skin configuration and click on .ini file (Skins - <Skin_Name> - <Skin_Name>.ini)

Extra:

You can also configure additional skin options by selecting "Manage" option via tray icon pop-up like: Skin transparency, On hover behaviour, Click thru setting etc.