I'm not sure why it won't install from the disk for you. I just tested my another company Combat Helicopters (Nemith Chinook and Huey), and it worked fine. However, I'm using Windows 10 Pro 64bit.
Captain Sim sometimes have a 9.99 euro sale (around the end of the year, or the beginning of the year), and at the moment, 9.99 euros, is around $US11.55, so you could save a bit by waiting for that (hopefully they'll have another sale in December/January).