As stated in the instructions, you should run the installation as root by becoming root (sudo su), else it doesn't get the correct ENVs for root.
The correct link for the most up-to-date documentation is https://iri-playbook.readthedocs.io/en/feat-docker/getting-started-quickly.html
Note that the command only has one <, i.e.:
bash <(curl -s https://...
Disclaimer: I am not a developer
Have you tried following this tutorial?
Comparing the code might help.