This occurs on a K2 4.6.11 installation when you are deploying and activating the K2 for SharePoint app for the first time on a SharePoint 2013 on-premise environment. During the "Registration Wizard" step, when you click on Next, nothing seems to happen and after 30 seconds it will seemingly just reload the "Registration Wizard" step. You cannot proceed further.
The SharePoint 2013 installation was upgraded from an earlier SharePoint 2010 installation. When you run a Fiddler trace during the Registration Wizard step, you will notice that it will try and load old versions of jQuery, for example version 1.x or older.
It seems the migrated Web Application was loading an old version of jQuery.
This seems to be the cause of the issue, since K2 does not support anything lower than jQuery 2.x after K2 version 4.6.9 was released.
If you disable the jQuery 1.x code on the SharePoint site and re-run the Registration Wizard, it seems to resolve the issue.