Complex sentence: In 1920 they played a promotion playoff with El Porvenir but lost 3--2 on aggregate, one year later they secured promotion to the Primera, and made their debut in the 1922 season, where they competed well, finishing in 6th place.
Split into simpler sentences: In 1920 they played a promotion playoff with El Porvenir but lost 3--2 on aggregate. In 1921 they secured promotion to the Primera, and made their debut in the 1922 season, where they competed well, finishing in 6th place.