Hi Lukazs, It has been tested on SQL 2005, 2008, 2008 R2, 2012 and 2014.
There is a Help article with this and other the things that it needs:
Deployment and Installation > Installation > UC Reporter > System Requirements
Another article here that SQL Express is only good for very small sites:
Prognosis UC Reporter > Setting up UC Reporter > Site Configuration > SQL Server
Apparently always on should be OK according to this post but not widely used:
https://online.prognosis.com/forum/reporting/is-alwayson-highavailability-supported-in-prognosis-reporting/
Here are some other articles you'll find to be interesting about UC Reporter:
https://online.prognosis.com/forum/reporting/uc-reporter-vs-advanced-reporting/
https://online.prognosis.com/forum/reporting/uc-reporter-install-to-monitoring-node/
https://online.prognosis.com/forum/reporting/uc-reporter-and-prognosis-11-x/
HTH