When you look at the two columns - "Select Device" and "Select Software" -- to me... the way these are presented, it is implied that both are equally required parts of the form. "Please choose.." and "select".

When one selects a device, since its on the left and it seems required... The accordion widget then appears and expands downward, and you're to select Mac or Windows..  Which to me are both "software." Therefore in my mind, if you are to select "windows" (which is what I use), the place you click is in the identical column "Select Software" was. So in a way you are tricked into thinking you're doing the right thing and selecting "software" when you click "windows." Even if that wasn't your OS, you're still selecting "software" and think you're doing the right thing.

Looking back at it, I see now that there is a word "or" in there, but it's easy to miss. In any case, I would change the way the page works.

Been using computers all my life, 45 years old, BSEE, musician, and I worked support at a software company 15 years ago.  It's a minor gripe, but I would change this. To add to this.. if you click the "Software" heading at the top of the page... you're taken to the same downloads page with the ambiguous branch decision described above. If you've already missed that you could select the "select software" drop-down before "please choose software", it just makes you more frustrated.

I resorted to using google search "site:rme-audio.com digicheck download" and STILL failed. 

By the way, I have had my RME UCX for 10 years, and I only discovered that this digicheck thing existed today when I decided I wanted to find some kind of spectral analysis to help me to balance the output response of a new keyboard amp.