Hi sixtythree
I am not with Laminar Research; just a flight simmer.
My suggestion is as follows:-
1. Check that your computer meets the required specifications. Particularly the recommended specifications for best effect. Although not mentioned your PC needs good cooling as the CPU and GPU generate heat. The specifications can be found at the following link at https://www.x-plane.com/kb/x-plane-11-system-requirements/
2. If there is some doubt download the digital demo version first. The demo version when downloaded is a full version but restricts you to a time limit of about 10 minutes from a particular airport.
3. If it all works then proceed to buy/purchase. I did not venture to this stage as I have a disc version bought elsewhere. I am of the opinion that you will be lead through the purchase phase. When payment is acknowledged you will receive a receipt number and the all important "password key"
4. When you have the key, open up x-plane and you will be prompted when and where to provide the details. The full version should then open and you will be able to fly from you choice of location.
Good luck and welcome to X-Plane
Glenn