Have you tried to delete the file you have re-download the software?
That usually happens when the app is cracked. But it could happens even if the download is corrupted or the app is not properly signed. Try to download it again, and if doesn't work, contact Panic.
What other unarchiver?
Something seems off?
I have used Transmit for a long time 15 years or more - never had an install issue and even lost my license a few times and they sent it back within minutes
Usually incredible support - and awesome FTP for mac
Not sure what those extra files are in the original post - I don't see those when I download the file from the website?
@camelia Might I suggest ForkLift as a replacement for Transmit if the requirements are FTP usage. Granted, I don't personally do much FTP'ing anymore - ForkLift is so much more than a FTP(FTPS) app for the Mac - I use it as my go to file manager. You can try it out for free as a trial at www.binarynights.com
Anyway, that is all. I hope that you get that refund for Transmit.
Thanks to all I am going to ask for a refund
Since I did not see anyone else mention that, would you kindly try a fresh download one more time, and then after it extracts, move the truck to the Applications folder, and then see if it starts without a hitch? It appears you are not moving it to the Applications folder, and what harm might come from trying once?
Also, since you paid for it, try to get the devs have a look at what is going on, in the interest of the larger Panic community.