Citizens from the EU, EEA member states and Switzerland don’t need a visa to enter the Schengen Area in which Austria is part of. Participants, who are citizens outside of the visa-free countries, need to apply for short stay visas. You can find all important information on the website of the Austrian Federal Ministry for Europe, Integration and Foreign Affairs https://www.bmeia.gv.at/en/travel-stay/entry-and-residence-in-austria/.
If you need an invitation letter, feel free to contact us. However, please note that we cannot take over any visa-related costs nor responsibilities.