I used VirtualBox 6.0 to create a VM (2Gb RAM, 40GB VMDK), installed Ubuntu 18.04 desktop (minimal version), then downloaded and installed the 7.2.0-1 platform and the Kafka, SQS, Redis, and V8embed plugins (attempting to reproduce my own HPCC VM). It all installed fine.
I used this command to start the environment:
sudo systemctl start hpccsystems-platform.target
ECL Watch said the Thor Slave process wasn't running.