There are frequent trains from Copenhagen to Aarhus and also many from Hamburg (and thus the European train network). You can use the Journey Planner to schedule your trip. Danish rail services are called DSB.
Set the GPS to Høegh-Guldbergs Gade 6B, 8000 Aarhus C. Please note if you drive from Copenhagen you need to pay toll (DKK 240) if crossing the bridge between Zealand and Funen. The parking spaces right around the auditoruim is limited. It is possible to park at the Department of Computer Science, Åbogade 34, 8200 Aarhus N for free and walk to the venue (15-20 minutes walk).
The AIAS Auditorium is located in the Univiersity park right in the city centre at Høegh-Guldbergs Gade 6B, DK-8000 Aarhus C. You will be able to walk to the venue from most hotels in the city centre in about 15-20 minutes.
Bus: In busses you need to pay in cash (DKK only), a ticket costs DKK20 and is valid for 2 hours. You can also download the MidtTrafik App and buy tickets via the App. However, the app is only available in Danish.
Letbanan (tram): Remember to buy your ticket before getting on the Tram. Tickets cost DKK 20 and are valid for 2 hours. Can be bought on the MidtTrafik App or on machines (cash or credit card) that are available at most tarm stations.
Taxis accept cash and most credit cards.