Ahh. Right. Thanks for bearing with me as a new user who is trying to figure things out.
Yes, I was on that community at lemmy.ml because I happened upon it by following links from lemmy.world I think. I clicked the big green Subscribe button at https://lemmy.ml/c/lemmy . I got a dialogue box "Subscribe from Remote Instance. Enter the instance you would like to follow this community from", and entered aussie.zone
This process worked fine for other communities I subscribed to.
But for this one I got the "Server error" message. (I was later able to subscribe successfully by copy-pasting the community address into the aussie.zone search.)
My hope that we can create an easy-to-use fediverse alternative to FB groups and events is literally why I'm here. Help me make this happen!!