The quickest way is to use MIDI to sync the Volca Sample and CV/gate to sequence the MiniBrute. Connect a MIDI cable from the Beatstep to your Volca Sample using the minijack-to-DIN adapter supplied with the Beatstep. Then connect monophonic 3,5mm patch cables from Beatstep's CV and Gate outputs to your MiniBrute's pitch and gate inputs.
However, MIDI in Volca Sample is implemented so that channels 1-10 represent samples 1-10, so you have to use the MIDI Control Center software to change the sequencer channel somewhere between 11-16. Otherwise the sequencer will also play one of the samples.
I hope this helps!