All bonuses which are given on the basis of a qualifying deposit have an activation requirement: This is the turnover required using your own withdrawable balance before you can use the bonus money. In most cases it is one-time the qualifying deposit amount.
You can use the qualifying deposit amount and the bonus amount together in one bet. If you e.g. deposit €100 and get a €20 deposit bonus, you can place a bet with a total stake of €120 as you fulfill the activation requirements with this bet. In case of a fixed odds bet however the price has to be at least 1.50.