I noticed when people put up a battering ram there were like 6 slots to be occupied. However, I think the interface was covering up the text to tell us what to click to become part of the battering ram team. Did this happen to anyone else?

I'm fairly certain to "become part of the battering ram team" all you have to do is stand inside of the battering ram.

There was a notice underneath interface and you could guess it said something like hit (enter key hear) but I couldn't see it. Standing there seemed to work though... oddly.

Yeah, I got underneath it but it didn't really seem to engage or anything. I wasn't sure if it was working as intended. I wish it gave an announcement or animation that you are helping push it against the wall.

All you need to do is stand next to the ram. More people standing next to it makes it move faster and hit faster.