Have you tried allowing full permiss manually? Changing the exported folder to another location? Have you exported with .zip software or with the built-in mac zip to decompress(Recomended) ? Have you tried adding on a .dmg file and execute it? All this fixes/solutions are in the links, have you tried all of them and none worked?
We had people with the same problem about the file is damaged or similar but all them fixed in one or other way and working without problems.
Try to look in google about how to fix the “Downloaded .app is damaged and can't be opened” problem to see if some one works, in that case please, let us know which solution worked for future users with the same problem.
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Maybe this can work for you?: