I'm not sure you even have to do that any more (add to the vboxusers
group I mean). Mine seems to work without - can't hurt to do it though.

I see no reason to compile anything. When I've dled Vbox (you have to go
get every new release, it gives you a link when you open it when there's
an upgrade) ... when I've dled it it comes as a .deb, which has an
association with synaptic so I just choose open once it's downloaded and
sit back and watch.

My two penn'orth on what extra you might need to do: go into the
settings for Vbox and /or your virtual machine and add a USB adapter,
plus anything else you might need, to its configuration. It's all done
graphically and is quite straightforward with maybe just a bit of trial
and error. You can also do it on the fly from the Vbox devices menu.