I finally received an answer from somebody at ugo. Here's what they said:
Hi Drew,
Unfortunately, I don't know exactly what's going on with PlayLink; they were
a service that was provided through another company owned by us. I can only
imagine that it's going the way of the dinosaurs. ;( I'll ask around and
see if I can find out anything, let's hope it can be resurrected in some
form as I understand there are lots of people who enjoyed playing it.
Best,
Eric
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Eric "Scoop" Eckstein
Editor-in-Chief, UnderGroundOnline