Finally managed to root after three days of suffering.
Some hints…
Foothold:
You need to know your target. Firefox tells you, on the higher port. Just look closer. Then, a quick google search can give you a tool for shell. No need for guess work as some other comments say.
User/Root:
I managed to get every user shell without password, including administrator (started some service, and added my own keys). But, wasn’t enough to decrypt the files for flags. Finally, got a nudge from someone that I needed to find a file to get some creds. And the portal is needed here. Decryption only works if logged-in with password I guess! Didn’t know that, and wasted 2 days. User/Root flags need exact same steps, just a different set of THOSE.
PM for any nudges.