I have done everything according to manuals from https://jfrog.com/open-source/ :
My Ubuntu version is 20.04. Since there is no "focal" in https://releases.jfrog.io/artifactory/artifactory-debs/, I've added "bionic":
$ cat /etc/apt/sources.list.d/artifactory.list
deb https://releases.jfrog.io/artifactory/artifactory-debs bionic main
Then I've installed jfrog-artifactory-oss version 7.12.6 and tried launching the service. It has launched, but browser, connected to ports :8081 or :8082 of localhost, shows that 3 services don't start:
So, what does it need?