I usually use Ubuntu.
You can find the image file here https://eu.dl.twrp.me/fp2/
You need to use fastboot: apt install android-tools-fastboot
Short guide: To install, boot your phone into the bootloader (Power+Vol down), run fastboot flash recovery <filename.img>, reboot into recovery.
Long guide: ✏ Using TWRP on the Fairphone 2