Participants are responsible for making their own arrangements.
Vienna is busy in June, so it is advisable to book accommodation as soon as possible.
There are many hotels within walking distance of the Dominikanerkloster. Some will allow you to make a provisional reservation without payment and with no penalty until nearer the date.
The guest house of the Teutonic Order, located less then ten minutes away, has rooms without breakfast for €119 (single), €179 (double). Website: https://gaestehaus.deutscher-orden.at/
A small number of rooms are available at the Schottenstift, about 15 minutes walk away. 95 euro single, 160 double (https://www.benediktushaus.at/)