You can get to the Johannes Kepler University Linz (JKU) easily by public transportation (tram lines 1 and 2, direction: JKU | Universität).
From Airport
If you arrive at Linz Airport (LNZ), you can take bus line 601 to Linz train central station. You can find the bus schedule on the Airport’s homepage and get current information on the departure times here. From the train station you can then take the tram to get to JKU (see below).
If you arrive at Vienna International Airport (VIE), there are frequent ÖBB Railjet and IC train connections that run from Vienna Airport to central train station Linz Hbf. An overview of all connections is available in the ÖBB Trip Planner called SCOTTY. Also AIRail is available with participating Star Alliance carriers, see also the ÖBB website. From the train station you can then take the tram to get to JKU (see below).
From (Train) Central Station
You can take either tram line 1 or 2, which both bring you to university (direction: JKU | Universität). There is a tram almost every 10 minutes. A ride from the train station to the university takes around 25 minutes. You can find the travel planner (incl. latest departure times) here.