Are you holding ‘Option’ down when it boots? So as to access the GNU GRUB menu?
Quick search:
First look: Linux Mint 21 beta, on a 10 year old Mac! [24:14 | JUL 17 2022 | Veronica Explains]youtu.be/D7wOcIvWdxc&t=210
Chapters:
00:00 Intro
00:26 Why use Linux Mint?
03:29 Booting from, and playing with, the live USB
06:51 Release notes and installing Linux Mint
09:50 First impressions of the new Linux Mint install
10:56 Walking through the “First Steps” guide
14:45 Updating for the first time and playing with the Panel
15:53 System settings in Linux Mint
16:32 Software Manager and installing OBS from Flatpak
18:21 Customizing the Panel (taskbar)
19:52 Trying OBS from the Flatpak, testing the camera
20:24 Other applications shipped with Linux Mint
22:56 Parting thoughts
Edit: added below
Another quick search:
Noob Guide to Installing Linux Mint on 2014 MacBook Air [07:47 | FEB 05 2024 | jailbrayk]
This process should work on any Intel Mac pre 2018 (without T2 security chip & secure boot). Thanks for the suggestion to install Linux on this old MacBook Air! It has brought new life to this old computer and I am really enjoying getting to know Linux, as I have never really used Linux in this capacity. Let me know if you would like a more in depth video of how I set up my Linux environment!