I, too, am unable to activate the anti-theft feature on Emsisoft Mobile Security. I uninstalled Emsisoft from my Droid Maxx, turned my cell off and then on, installed Emsisoft once again.
However the anti-theft feature just won't recognize my Emsisoft account. I tried to use Google+ and a message popped up saying "a malformed response" was received and says to make sure I am using the latest version. My apps all update automatically. So, I cannot use Google+ or my Emsisoft Account, nor can I create a new account. I am caught in a loop...
All the other features are working fine and Emsisoft is protecting my phone, so that's all good.
Shall be watching for the solution to activating the Anti-theft feature to come available.