From memory….
If you open Driver Manager after installation it will say you need to either connect to Ethernet or insert the installation USB. Using the Installation USB is fine.
It should then automatically detect you have a Broadcom WiFi module and just give you a checkbox you can click next to the correct driver.
It will install the driver from the USB, say you need to restart and then you should be done! Upon rebooting your Mac should immediately recognise available WiFi networks and let you join them.
Amazing!
That distro is highly deserving of the praise it gets.
Hope you get on ok with the rest of Mint (and Cinnamon) 👍