It’s not too hard.
It won’t install it if it is the wrong one.
Most newer phones you will want Bravearm.apk
I have a Pixel 5 and that’s the one I used.
On my older 2016 phone I used Bravex86.apk
Just download and in file explorer click on the downloaded .apk and it will prompt you to turn on install install unknown apps, if it’s not already on. You can easily turn this back off after if you so choose.
https://www.reddit.com/r/bravebrowser/comments/rc2uri/which_apk_file_should_i_select_to_install_brave/
Hope this helps.