Using a nRF52832-DK and nrfconnect-2.0 on Win 10 everything works well.
But using that with Ubuntu 18.04 requires more installation documentation!
1. it seems, that the segger jlink software 6.20b (exactly that version) must be installed ahead.
2. even when the user is added to dialout, "Error while setting up device ....: Keine Berechtigung, cannot open /dev/ttyACM0" is reported.
starting as su works.
crw-rw---- 1 root dialout 166, 0 Sep 2 18:51 /dev/ttyACM0
Please check, why it's required to run a su, I would prefer to run it as normal user in the dialout group.