The free test at the congress venue is an antigen test. This is valid within the EU, which means that you can travel with it.
For travellers from outside the EU, a PCR test is mandatory for travelling.
For travellers from outside the EU, if you have to show a negative test to travel back to you country, then it needs to be a PCR test. These can also be performed on location, but cost €59.95. Please note, this test result is only known after 24 hours.
An appointment can be scheduled in advance for this at PCR test link