I liked this challenge, but like so many on here, got stuck on the last part before doing as many suggested and googling the key terms.
Here are my hints:
1st part: Listen to the audio, what kind of sounds are they? Tools are available online as well as scripts to decode.
2nd part: Look at each number. What do they all have in common? Google that word plus a word related to cryptography.
Feel free to DM me or catch me on Discord.