My situation is slightly different but related. My home studio is in another building without Internet access (computer there is JUST for music recording). I just bought Sonar and thought I was downloading a master file I could then copy to a mobile drive or DVD but it installed it on my home PC. Now how will I get it installed on the right computer? Yes I know there can be on only one and have no issue with uninstalling it on my house pc. Surely there must be a simple way and I am not the only person in this situation. I tend to rush a bit sometimes and could have easily missed an instruction or 3 at some point doing the download. I would have bought a boxed copy had I known.

You don't have to uninstall Sonar if you don't want to, Heyrag. You are allowed to install Sonar on all your computers as long as you don't use them concurrently.
 
For example, it is fine to install Sonar on your studio computer (in the other building) your desktop in your house and your laptop with a single license. It would not be within you license to lend you laptop to a friend to record a live gig while you simultaneously record a band in your studio. Or if you have multiple studios where you record concurrently, you need multiple licenses. 
 
If you want to record on one computer in your studio and mix on your laptop later, that's fine and only requires a single license.

That's for the reply, and all GOOD to know BUT my problem is how to install it on my music (a desktop) computer that has no internet access, that is my bigger issue, I could go out there, unplug everything, carry it into my house, log on to the Internet and do it like that...but what a PITA! I'ld like a disk...or a file to put on a disk or Mobil drive...

All the installer files should be in the C3 DL dir on your notebook. Use the cog if you're not sure where that is. Pop those files on a big (or several) data sticks or a usb drive and sneaker them over to your desktop. You'll probably want the installers on external BU media anyway. They are just files. Include the c3 installer. Run the C3 on your desktop with its DL dir set to wherever you put the installer files. It should start up, validate the files and start dumping them to your C: drv. I run the installer manually for better control, but apparently C3 isn't happy about that. Easy peasy.

Also, after sneakering the files to your studio and installing them you will need to do the manual registration.
 
Try looking here
C:\ProgramData\Cakewalk\Command Center\Downloads
 
If you hadn't downloaded already you could login and go here...
https://www.cakewalk.com/My-Account/Products
and then you can download the files without installing.
 
Offline registration instructions
https://www.cakewalk.com/Support/Knowledge-Base/2007013384/SONAR-Platinum-Professional-Artist-Offline-Authorization
 

Thanks, I think that info should get me in there. I downloaded the files again, and will try the offline activation method. Should work.