Download the file, run zsteg on it and you'll get a pastebin link. https://pastebin.com/hvgCXNcP
.
Visit that and you'll find base64 text that decodes into a zip file.
Save the zip file and open it but its password protected.
So run zip2john and get the hash and dictionary attack it with rockyou.txt
You'll get a password of kitkat.
After catting flag.txt run a ROT47 decryption on it and you get.