I just installed Rebit 5 on two brand new Windows 7 Home Premium laptops (exact same machines, though one might have had a few more Windows updates installed than the other). One installation worked flawlessly, but while that was running its initial backup, the other showed no input fields above the list of available shares at all.
However, not selecting any of the shares that were shown, I could still click the "Done" button (or whatever its English label would be) to finish the installation. Rebit 5 then told me it would create an initial backup. Obviously, it had no disk to back up to, but by clicking the gear icon in the lower right corner I could get into the backup locations manually, and then the input fields for the NAS were shown as expected.
(Possible cause: that second laptop has its font size set to 110%, somewhere in the Windows preferences. The inputs show no titles at all though, and appeared fine when manually going into the backup locations settings afterwards, without changing the font size settings.)