The Mutan Brain module shown here does not seem to have any sort of clock / run outputs, so I'm not sure it's going to work as you expect it, actually.
Mutant Brain can output clock (tick / and run) as a trigger signal for all gate outputs. Working perfectly.
Configuration can be done here: http://mutantbrainsurgery.hexinverter.net/
As far as you are sending the standard start and stop midi signals from your Digitakt to the Hexinverter Mutant Brain, the signals can then be used in your rack to handle clocks and modulations accordingly.
But regarding your rack setup, you should familiarize yourself with the general modulation and sound generation capabilities. In order to play notes and sequences, which is probably what you have in mind for techno patterns, you need more CV modulation tools like envelopes and LFO's, maybe also sample and hold (s&h). To shape audio and sound you’ll need an amplitude modulation module like a VCA, a filter, a low pass gate and / or a mixer to which you can send the CV modulation coming from the envelope. If you stick with a small case size like this one, VCO + BIA is quite enough. Modular sound design is all about modulation rather than stringing lots of VCO’s together.
Hope that helps to make you dive deeper into the topic of modular synthesis.
