By default the Microbrute is set to multi triggering, but it can be set to single triggering using the Microbrute Connection software. The parameter is Envelope Legato Mode, and the settings are On (= single triggering) and Off (= multi triggering). You can also set the note priority (under Keyboard Parameters), which will also have an effect on how the notes and envelopes are triggered when you play the keyboard or notes are received over MIDI or CV/Gate.
For what you want to do the triggering mode and note priority don't matter since there is no overlap between notes when the sequencer is playing. That is, the gate is turned off between notes so the envelope will retrigger on every sequencer step no matter what triggering mode the synth is set to.
But this may help you get something close to what you want: On the Microbrute front panel, in the Envelope section, set the VCA switch to Env, and set the Release slider fairly high. Play a sequence and adjust Attack and Release to taste.