If you win a wager using a bonus bet, you will receive the winnings from the bonus bet as "Cash," which is withdrawable. If your wager wins, you will not receive the bonus bet stake back as part of the total payout and only the win amount. If the event you place your bonus bet on gets canceled, your bonus bet is returned back to you to use again on another eligible wager unless it has already expired.
For example, if you use a $100 bonus bet at +100 odds and win, you will receive $100, not $200.