At the age of 10 (2014) she sailed for the first time at a U15 Optimist European Championship in Dún Laoghaire in Ireland.

At the age of 15 Donner and Sebastian Slivon won the Austrian U19 Championship on Lake Traunsee.

Rosa Donner and Sebastian Slivon subsequently won several national[1] and international titles.

At the Trofeo Princesa Sofía regatta in Palma de Mallorca, the two reached 50th place out of 66 participants.

[citation needed] In July 2022 She and Slivon won a silver medal for Austria at the Junior European Championship.