I have tried this plugin on two completely separate and unrelated websites. Both times, I get the same problem, where the confirmation email is not being sent out. And looking at the support requests, it seems that I'm not the only one who's had this same problem.
Reading the comments from other reviews and support requests, the author seems very defensive and doesn't really offer any real advice to rectify issues.
I would give this plugin zero stars if I could. It's not worth it, in my opinion. And I would HIGHLY RECOMMEND that you DO NOT BOTHER EVEN TRYING THIS PLUGIN.