If you travelling by air, it is possible to catch a train directly from Airports in Düsseldorf or Köln/Bonn to Bochum’s main train station (Bochum Hauptbahnhof).
You can plan your route to Bochum and buy tickets on the Deutsche Bahn website Deutsche Bahn website: https://www.bahn.com/en
Once you arrive at Bochum’s main train station (Hauptbahnhof), you can then reach the Ruhr-University, which has its own station, easily by catching the underground (U-Bahn) train U35 (CampusLinie). On workdays, the U35 (going to Bochum Hustadt) departs in five-minute intervals, and it takes less than 10 minutes to go from the main train station to the university station (Ruhr-Universität, Bochum).
Bogestra is the local transport authority in Bochum, from which you can plan local public transport. If you are using a smartphone, the most practicable option is to download their app "Mutti"
Bogestra: https://www.bogestra.de
Mutti App: https://www.keine-ist-wie-mutti.de
DB-navigator app: https://www.bahn.de/service/mobile/db-navigator
Please note that for U-bahn, regional trains (Regio), and bus, it is possible to buy a single ticket for €9 for all of Germany, which will last all of June. This is a special measure introduced by the government to combat the cost-of-living crisis. The ICE,IC,EC trains are excluded from this. Please don't buy single tickets for local public transport if you plan on using it more than three times in the country in June. The €9 ticket can be bought from ticket machines, on the Deutsche Bahn App "db-navigator" or on the apps of any local operator; in Bochum, this is the Mutti app from Bogestra.
Once you get off the U-Bahn at the University station, you should cross the footbridge in the direction of the main campus (to your right). If you descend the levels of the campus in a generally straight line you will reach the venue at Beckmanns Hof, the convention centre of the University. You can see where it is on the campus map below
But be aware that Google will send you on a very long round about way, if on foot, that doesn't make use of the layered levels of the campus which can be navigated much more quickly. We will send update with exact instructions shortly, as the descending is not always intuitive.
For more detailed information on how to reach the university, e.g. via car, we refer to the univerity's own website https://www.ruhr-uni-bochum.de/anreise/index_en.html and the all mighty Google Maps.