file cannot open

The file is corrupt (and MuseScore says so when opening it):
Measure 9 Staff 1 incomplete. Expected: 7/4; Found: 15/8
Measire 10 Staff 1 incomplete. Expected: 7/4; Found: 132/72
It does then open it.

This file apparently was created/last saved with MuseScore 1.2 on Windows (strange, you say you're on a Mac?), which doesn't report corruptions.
It is outdated since several years now, we're at MuseScore 2.0.3 now, and even in th 1.x branch we had a 1.3, which may hae that bug fixed that causes 1.2 to crash on that file.

There's indeed an 8th note too much in measure 9 and those nested tuplets in measure 10 do look rather strange too (timesig is 7/4, nominal and actual):

Probably done via copy/paste, which indeed, esp. in 1.x, was a way to corrupt scores. I see no weasone to not upgrade at least to 1.3, but you should also consider switching to 2.0.3 (I'd keep 1.3 around though, both version can coexist and even be used at the same time on the same machine). May not be an option of really old Macs though, for 1.x see https://musescore.org/en/download#For-older-versions-of-Mac-OS-X

MuseScore 1.3 BTW does not crash on it.

Attached a fixed version with those 2 corrupt measures emptied, as I'm not sure about the desired content, you may re-enter them using the imague above