It's not a simple process but if you are patient and follow the guide
to the letter, it will do most of the setting up on its own.
The important bit is the "to the letter", though. If you mess something up, sometimes even starting over won't fix things.
There are also two ways to "pair" the VA with HCS to the game.
1) It can detect your bindings and set up the VA accordingly. This is the risky way. For me, it's always been about 50:50 if it's gonna work or not, but if it does, it's less work afterwards.
2) Let it create a custom binding file with pre-defined VA commands. This is the safe way that works every time, but you then have to go the the Controls settings in game, select the preset it created and bind your HOTAS (or whatever you're using) to the secondary column.
That's the way I do it usually.
In either case, prepare yourself for about half a day of Fiddling with Stuff.
You have to prevail. It's worth it, definitely, but it can be a harrowing experience if anything goes wrong during the process.
If you have any issues, I
strongly recommend joining their Discord server where you can get help for your specific case and talk with somebody in real time to troubleshoot it.