the easiest way is to format a usb. download the file from Brave Browser - Fast Install Script for Ubuntu, Mint and derivatives
Save it to a usb drive, eject it, boot back to Linux, plug in the thumbdrive you saved it to and copy it over and then complete the steps outlined in @vasileios post at the same link which are from the terminal:
I would suggest first when you get it copied back over that you run:
sudo apt update && sudo apt list --upgradable -y
If there are any updates to install:
sudo apt upgrade -y
and I also like to run
sudo apt autoremove
to clean out any old stuff before installing anything else.
cd Downloads (or wherever you copied it to)
chmod +x ./install_brave_browser.sh
./install_brave_browser.sh
Provide sudo/root password if prompted, not “connie” password.( the one you made during the install for root) and watch it go.