[CanAutM3]

Spacers have no impact on alignment with the wheels straight, but will affect the Ackerman angle when the wheels are steered. This however should not have an effect on the ability to align the car. Worse comes to worse, you could get the car aligned without spacers and re-install them after the alignment.

Lowering springs will increase negative camber. If your car was borderline, it is possible they cannot bring the alignment within BMW spec with the springs installed. If that is the case, you’ll simply have to settle for an out of BMW spec alignment that works (i.e. more camber while keeping toe within stock specs).