Santiago is 5 hours behind Madrid
Best overlap: 1:00 PM to 6:00 PM in Madrid is 8:00 AM to 1:00 PM in Santiago.
If you set up a recurring sync, 1:00 PM to 6:00 PM in Madrid (8:00 AM to 1:00 PM in Santiago) is the natural home for it. Around 5 hours of overlap is enough to work comfortably, as long as meetings don't drift to the end of one team's day.