If your friend is already a card holder then the online enrolment is a somewhat pointless step.
I recently gave my referral to an existing Silver simply by calling GGL. I spoke to them on the Saturday morning and by Tuesday afternoon my friend was upgraded to Gold.
If your friend is not currently a BAEC member or a Blue then the online link is probably the best starting point but I got the feeling that GGL would also deal with this for you if you asked them to.