A extensively description in german can be found at http://wiki.nelson-it.ch.
To install the ERP on ubuntu or Debian/Raspian add the PPA
Linux | PPA | Version
---------- | ----------
Ubuntu 18.04 LTS | http://ppa.nelson-it.ch/ubuntu bionic main | 7.5
Ubuntu 20.04 LTS | http://ppa.nelson-it.ch/ubuntu focal main | 11
Ubuntu 22.04 LTS | http://ppa.nelson-it.ch/ubuntu jammy main | actual release
to the /etc/apt/source.list
and add the key with
apt-key adv --keyserver pgp.mit.edu --recv-keys EA8389D4
or download nelson-ppa.gpg to /etc/apt/trusted.gpg.d.
Then select the package mneerp for installing.