FanDuel Sportsbook usually offers one of two different sign up bonuses through which users can receive free bets:
Risk Free Bet - To unlock a free bet via FanDUel's risk free bet offer, you must first deposit and place a bet. If you're bet loses, you will be granted a free bet amount matching your qualifying bet 100% up to $1,000
Bet $5, Get $200* - With this offer, users just have to bet a minimum of $5 in order to receive a free bet worth $200. This is preferable as you're rewarded whether your bet wins or loses, but FanDuel only occasionally offers this bonus, with the risk free bet being the primary way to get free bets on FanDuel.
*Amounts may vary