Complex sentence: Upon arrival, they had to head to Plaza de Armas where they must participate the fireworks festivities called "Festiva de Fuerza" and where teams received a small box of matches from a man for the departure time the following morning.
Split into simpler sentences: Upon arrival, they had to head to Plaza de Armas where they must participate the fireworks festivities called "Festiva de Fuerza". Once there, teams received a small box of matches from a man for the departure time the following morning.