You can download files onto your desktop (or wherever you've specified in your browser settings) from their website if you want to bypass the computer-specific app altogether. Go to the website, make sure you're signed in, find whatever item you want in the on-screen folder, then right-click it and choose the Download option from the drop-down menu. This works fine on both my Mac & my PC (Windows 7).

BTW, make sure you type "Dropbox.com" correctly in your URL box: I once mistakenly wrote it as Dropbpx - a common typo - and it sent my AV warnings into overdrive. So no doubt some rogue bought that domain name for the very purpose of harvesting the unwary. Anyway, I've always been able to retrieve stuff from their main website with no problem.