(text borrowed from Bandcamp.com)
How do I unzip my album download?
When you download an album, it arrives on your computer in a compressed format called zip. Before you can add the music to your library and listen to it, you’ll need to decompress, or “unzip” it. Doing so is very easy:
If you’re on a Mac, double-click the file. You’re done.
If you’re on a PC, right-click the file and choose Extract All… You’re also done. Don’t see an “Extract All…” option? Try renaming the file to something simple, like “music.zip”. The important thing is to make sure the name ends with “.zip”. Then right-click it again. You should now see “Extract All…” in the menu. If you still don’t see an Extract All… option, double-click the file. This will open a window listing the files inside. Press Ctrl+A to select all the files, then drag them into a folder or onto your desktop. This will extract them, for sure. What!? That doesn’t work either? You may be amongst the elite few who simply don’t have unzipping software built in to their PC. Easy to rectify: just go here and get it.
I downloaded music, now how do I get it into iTunes or Windows Media Player?
To add music to iTunes, just launch iTunes and choose File > Add To Library.
To add music to Windows Media Player, you can either: a) select the audio files, then right click them and choose “Add to Windows Media Player List”, or b) drag and drop the audio files onto the Windows Media Player window (if that doesn’t work, try the drag/drop operation again, but make sure the Library tab is active in Windows Media Player first).
When I try to unzip my album, I get an error message. or
When I try to unzip my album, I get a message saying the zip file is empty. or
When I try to unzip my album, I’m prompted to enter a password.
All of these errors indicate the same thing: that the downloaded file is incomplete, probably due to a hiccup in your internet connection. The solution is to try downloading the album again. Album downloads can be pretty large, so if you’re on wireless you should definitely try plugging directly in. You can verify that your download is complete by right-clicking it and selecting Properties (or if you’re on a Mac, by clicking it and choosing File>Get Info). The size should match the file size indicated on the download page.