how to use sensored BLDC as stepper motor
It is all down to the controller. While it is possible to somewhat control the position of a BDLC motor (not as precisely as a stepper), the controller has to support this.

The controller you link is a standard ebike controller and this won't work to have any precise control.

One DIY solution (which I would probably do) would be to take the controller apart, cutoff / unsolder the control electronics,  keep the power/sensors stage, hook up an Arduino with and write a custom firmware to directly control the power stage. This will require a bit of electronic and programming knowledge but can be a fun project, especially if you want to learn.

The other solution is to try to find a BDLC controller which can specifically control the position or RPM but that might not be easy / or expensive.