Quite often doing K2 installation you may run into the “User Profile Sync Connection Task Warning” warning during Configuration Analysis stage:
Warning itself contains a lot of information as well as links to extra details, but it keep confusing people in need of quick fix for this warning 🙂 All you need to do is (as usual) detailed in official K2 documentation but for some incomprehensible reason it is very difficult for all of us to find relevant nugget in documentation, let alone read it all beforehand 🙂 But it is there really:
OK, enough referring to documentation and preaching about virtues of reading it. Here is what you need to do to fix this warning. The install user has to have permissions on the UPS. If you are installing as Administrator, for example, then check if Administrator has permissions on the Administrators and Permissions tabs for the UPS service. Below you may find a bit of visual aid which hopefully let you not to get lost in the thicket of SharePoint UI.
Sorry for absence of Halloween themed pics in the post at such a day, but I hope that information here may be useful to someone  (giving amount of times I heard questions about this warning, it definitely should be useful).