Dosbox uses an "emulated" hard drive so even if you mount a drive with 100Gb free, Dosbox will show a different amount. There's a parameter you can enter in your Dosbox shortcut (if you don't have one, make one) where you can manually alter the free space Dosbox will show. I think it's -freesize or so, check the readme.

But this error is not caused by a lack of free space. It's caused by too much free space - some games can't handle large amounts of free space and will instead end up with a negative number, hence thinking your hard drive is full. If you lower the amount of free space (just mess around a bit), it should work.

Thanks, I got it to work by making a file copy of the game and put in the folder and made a path, then mounted my cdrom and it installed.