I am (slowly) figuring things out. I got a reply from Support at NVcharts and they directed me to this website: Chart Download
Then you can find the charts that you want to download. You have to do it by year of release and I didn't know that so I just stepped down through the years until I found the chartkit that I wanted. I found the Windward Islands
kit but couldn't find the Leeward Islands
kit that I also purchased. I sent a reply email
to nvcharts asking about that set of charts and expect to hear back from them soon.
Anyway, you enter the charts that you want to download and click on the download button and they will load to your computer as an exe file. (I'm on a PC) When you run the exe file it will ask for your serial
numbers, name and email and then it will install the charts. They recommend saving them in C:Chartkit/BSB. That's where I installed and then pointed Opencpn to that subdirectory and everything seems to work.
I'd write up something quick but we are getting ready to cruise
and are up to our ass in alligators but once we get going I will probably have more time.