Vienna is 6 hours ahead of Medellín
Best overlap: 8:00 AM to 12:00 PM in Medellín is 2:00 PM to 6:00 PM in Vienna.
Keep meetings inside 8:00 AM to 12:00 PM in Medellín — that maps to 2:00 PM to 6:00 PM in Vienna. Vienna is 6 hours ahead of Medellín, which gives you a solid 4-hour window. Book earlier in it and neither side is rushing. These times hold for most of the year, but Vienna's daylight saving (which Medellín doesn't use) shifts them by an hour twice annually.