1. CyberChef -> Extract Files, then ignore the zlib's and the mp3's and find the embedded PNG.
2. Have a teammate that had watched a specific Numberphile video and that recognizes the human cipher used: https://en.wikipedia.org/wiki/The_Ciphers_of_the_Monks
3. CyberChef -> Magic, learn that it is hex-like data and remove spaces, to get https://git.io/JtJaX, and the `flag{th0s3_m0nk5_w3r3_cl3v3r}`

Original writeup (https://gist.github.com/AshishMahto/5571682d50ce4fad2b10d8c24dfc6552).