Install Plex via SSH on Ex2 Ultra?

How can I install Plex (or other apps) on my Ex2 Ultra via SSH? I’ve hit a dead end trying to install it conventionally (the Dashboard tells me “No apps available” and clicking “Install apps manually” gives me a EULA that never goes away). But is there a way to install it from the command line once I SSH in and download the Plex Media Server installer to whatever the right directory might be?

Following up: I found information elsewhere on how to get around the EULA by entering a string in the browser console. So, while I remain curious about this, the immediate problem has been solved.