Download the software and unzip/uncompress it.  There will be an .exe file.  Right click on that .exe file and then click on "Run as Administrator".  Install.  The manual suggests another folder than the default Program Files (x86) one.  So select just the folder with Program Files.  Let the installer do its thing.

Download the patch and copy the .exe file to the directory where you installed Plan-G (overwrite the old .exe file).

Run Plan-G (the .exe) -- I right clicked on it and ran it as administrator but you may not have to.

In Plan-G, under "File" dropdown menu, go to settings (do not build the database yet.  You have to tell Plan-G where your database/flight sim is located.  There will be multiple flight sims.  Go to X-Plane (assuming that's what you're using since you're here) and browse to your X-Plane directory then highlight the X-Plane.exe file and ok.  That puts the path and filename in the empty box in Plan-G.

Now you'll need to build the database.  Depending on your computer it can take awhile.  If you see some progress in Plan-G's status bar at the bottom, like "Reading apt.dat" or something, it's working.  If you have a lot of scenery, it will take quite a few minutes (or even an hour or more).

(The previous version was hanging when trying to build the database)

This now seems to be working with the "fix" linked to the other forum post (update to version 3.1.4.124).

First, I ran the installer as administrator (I'm on Windows 10 64-bit).  Then, after updating by simply copying the new Plan-G.exe file over to the install directory, I ran Plan-G.exe as administrator.

I entered the path to X-Plane (.exe) which is on my SSD and built the database.  This time I saw progress. 

After about 5-10 minutes, it looks like I'm ready to fly with Plan-G.

Wow, I don't fly around EGTN but your textures look really impressive.  I like the details of the buildings and hangars and even the truck/SUV.  Very nice.