Hi, welcome
Your Hifiberry dac is recognized by the system, and it looks like even jackd sound server is running. So your problem shouldn’t be related to the hardware, but
=> well, I’ve checked, while replying,the source code on Github and it looks like /zynthian/zynthian-ui/jackpeak/build.sh doesn’t exist anymore …
do you use https://os.zynthian.org/zynthianos-last-stable.zip as image (timestamped at 2020-09-06 01:39) or any of the later one ?
Have you done any software update ?