Zurich 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 Zurich.
For a call that suits both sides, look at 8:00 AM to 12:00 PM in Medellín / 2:00 PM to 6:00 PM in Zurich. You share roughly 4 hours a day. That's enough for regular meetings, but treat the window as prime time and guard it. These times hold for most of the year, but Zurich's daylight saving (which Medellín doesn't use) shifts them by an hour twice annually.