Anyhoo, it was my mistake - I tried to install the 64-bit version on my 64-bit computer. Silly me. The 32-bit version installed fine.
Didn't have any problems installing the 64-bit version, nor any download issues. All my frustrations stem from the lack of documentation, and error messages like, "This product requires another product in order to be isntalled," and doesn't tell you WHAT product that might be! Turns out I HAD the other product, but it wasn't in the same "default" directory that this 'dependent' product set as a default. The D|S installation routines are only a little idiotic, to say the least, but I have finally managed to get the content installed to the point where I can now start learning the program.
Don't bother looking for manuals - their documentation wiki is pretty half-assed, and several items in "Help" just say, "Coming Soon" (thanks, DAZ!!); however, each of the tabs in the program contain links to some fairly helpful YouTube videos on each of the program's major tools.