Without a bridge, you must be within Bluetooth range of the opener with your smartphone. This will not usually be the case, e.g. in a block of flats. I don't think the Opener is usable without a bridge.

You can programme the opener so that it opens the front door at certain times as soon as the doorbell is rung (Ring to Open). Then, for example, the children can open the front door themselves after school. This does not require a bridge.