However, it never finished- it hung up on some error message before completing, and never worked.
So it downloaded almost the entire chain and got hung at the end? What happened when you restarted the wallet afterwards?
Sometimes it would immediately give another error (not sure which error this was) and close, other times it would hang during the loading process, before it even shows the wallet and block progress, and after hanging for a couple hours I gave up and force quit and tried again from a fresh new start (deleted bitcoin folder etc).