How did their Spanish rivals of Florida attempt to damage this trade center?

The correct answer to this open question is the following.

Their Spanish rivals of Florida attempted to damage this trade center by encouraging the Yamassee to raid it.

Spanish explorer Juan Ponce De León claimed the Florida peninsula territory for the Spanish crown when Spanish navigators arrived at Florida in 1531. But it was Pedro Méndez de Avilés who was the first to establish friendly ties with the Native American Indians in Florida in 1566. He built the Fort of St. Agustine and a watchtower at Cape Canaveral. The Spaniards ruled Florida for almost 200 years. It was not an easy period because they always had rivals and other nation's interests in Florida such as France and Great Britain.

The answer should be:

Encouraging the Yamassee Native Americans to raid it.