I'm trying to install ITSI, but I don't see an install button. I can install it by downloading it manually from Splunk.com and install it, but what defer it from other apps while I can install UBA which is an enhanced app as well.
Since ITSI is a premium app the download option will not be available for everyone. If your company buys the ITSI premium app then you can request Splunk to provide access for downloading the package. Then download option will be available to you.