Problems setting up multisite Buddypress

I’m setting up as a multisite Buddypress, using BP Multi Network so each subsite has their own community.
I’m missing something, so am struggling to set it up on the first subsite
I’ve implemented it on another site, and there it offers me Buddypress options (registration pages etc) at the subsite level when I go to Settings on that site.
It doesn’t show on the same way, so I’m unable to set up the site to begin using it.
Any ideas? I have enabled Support Access.
Thanks, Neil.