I have no idea why one receiver ( Captive Works ) is so popular in Puerto Rico , Luisito what I can say is FTA is the ability to receive channels that are FREE and UNENCRYPTED .
In Puerto Rico you can get channels from Spain and Cuba , and plenty of good American English programming too.
FTA is not for receiving Dish Network without paying , that is called Hacking ( Stealing ), and it is not discussed here.
So if you are interested in True FTA , then I would recommend a Good Blind scan receiver , a Linear Universal LNB , and a Dish 90 cm or larger.