BCP is short hand for :
This tournament software can be reached https://www.bestcoastpairings.com/ and can be used for free for players and tournament organizers to track and control an event. Players can post information such as game scores to keep the tournament moving. Info such as what your opponents list is, what table you're playing at, who you're playing against, how much time is left in the round are all conveniently available to those using an account. The player app keeps all that info right there in your hands.
Players can be registered with out an email, but that will reduce the utility to that individual player. Said player may not be able to find their individual pairings and will need to reach out to an organizer with their list for upload, what their scores are and asking what table they're playing at. Due to that reason it's highly encouraged that players register for an account.
There are perks to having an account with a subscription but that is unnecessary in regards to playing at any one event and is not required for the Alamo GT participants. I have a subscription so i can look at my old list and follow non sponsored events.
Either way happy wargaming.
-David