Mac
Hm. I can't say I'm familiar with that issue. I have a few pieces of advice from experience and from looking up people's similar issues, though:
First, make sure that the files are in the documents folder, it's hard for the system to read/write if it's not in a read/writable directory.
Second, in your system preferences under Security and Privacy in General, make sure 'allow apps downloaded from anywhere' is activated, or else open the file via right-clicking and selecting 'open' in finder.
Third, I've seen people saying that re-ziping the files, uploading them via dropbox or google drive, and then re-downloading and re-unpacking them helps?? I have no idea why or if this would really work, but I suppose it's worth a shot.
I hope any of this helps, I'll keep doing some digging myself.
Thanks for speaking up!