With strobe photography the flash flickers on and off rapidly. It creates a series of separate images which break down complex movement into a series of instants. You need to work in as near darkness as possible. Ambient light will tend to illuminate the subject and destroy the strobe effect. Use a black background to your subject. The camera needs to be on a tripod with a long shutter speed selected, say 10 or 15 seconds.
For these images I set the flash unit to fire at 1 Hertz, that is 1 firing per second for a duration of 15 seconds. After a short countdown I set the flash going and the subject started doing ‘their thing’. Simultaneously the group started their camera exposures. Settings were: 100 ISO (or low); f/8 aperture; and flash output at 1/8th of full power. We made adjustments to the exposure using aperture and/or flash output. It’s best if the subject moves substantially from their original position. Any part of them which remains still will tend to accumulate exposure and start to white out.