Setting up a Flint 3 (GL-BE9300) as an AP with two vlan's

I’ve been directed via the subreddit to this thread. However, it somewhat confuses me. I’m trying to learn the commands that need to be performed since it doesn’t look like I can do everything that needs to be done via the GUI (even with LuCI) but, that thread, which otherwise seems to be doing exactly what I’m trying to do, is a bit too high level.

I don’t quite need an ELI5 explanation as I do have CLI experience in Windows, Linux, and FreeBSD but, I have functionally zero CLI experience in OpenWRT. I haven’t run any OpenWRT routers since the 802.11g days.