Innsbruck’s autobahn vignette between Innsbruck west and Innsbruck Kranebitten?

Hi everyone! I was in Innsbruck with my friends this weekend and now we’re heading back home to Italy. We accidentally took the autobahn between Innsbruck west and Innsbruck Kranebitten but we don’t have the vignette. Should we expect to receive a fine? Or is it a piece of autobahn free from the vignette? Just in case, is there anything we can do to avoid the fine? Maybe like buying a digital vignette right now or something similar? Thank you everyone!