Yea it "ain't obvious"
assuming you have an account set up you will need the Content Manager
1. AFTER you "buy" it it will give you a number (even though it says "download now" - all it gives is a pop up window with a number)
2. then need to run Content Manager
https://www.sonokinetic.net/contentmanager/3. That program will then manage your download - but you have to pick the server (US, europe, etc.) then it will determine which files it needs for the thing you bought, then at BOTTOM of that screen you sill have one more button to press to kick off download
NOTE everything is .rar format, but it will both download the RAR and UN-RAR it so you will end up with both RAR'ed and UN-RAR'ed wherever you have it download.