Hello Nicholas!
So, in this skin we have only 2 modules: AirMail 3 & TouchdownStats.
The installation is very simple, in both modules there is a folder called "core", and inside "core" folder we have more folders, which are usually the "modules", "templates" and "common" folder.
If you see the directory where your phpVMS is installed, we have this same "core" folder, and inside the same "modules", "templates" and "common" folder.
Basically, what you have to do is transfer the files from each folder to their respective location.
(EXAMPLE) So it would be like this:
You transfer the files that are in the "core/common" folder of the TouchdownStats module to the "core/common" folder of the directory where your phpVMS is installed. The same for the other files (core/modules in your core/modules phpVMS installation, The same for the other files)...
Some modules come with a .sql file, which creates some tables in your database, AirMail 3 is an example. If you look at the AirMail 3 module, we have this "airmail.sql" file. To upload it, it's also very simple, you need to go to your database (phpMyAdmin), enter your phpVMS database and click on the "Import" button located on the top menu, it will open another page that it will be there where you should import this file, click on the "execute" button and if everything appears green, success!