Cannot install RMF from apt

Hi, I'm trying to install RMF from apt by following this tutorial. In the Setup Sources and Installation of RMF section it says:

Next you will need to setup the source of RMF packages similar to the previous two steps. First authorizing the key:
curl -s http://rmf.servehttp.com/repos.key | sudo apt-key add -

Secondly adding the repository to the apt sources:
sudo sh -c 'echo "deb http://rmf.servehttp.com/ubuntu/main/ `lsb_release -cs` main" > /etc/apt/sources.list.d/rmf.list'

And now we are ready to install. Let's update our packages:
sudo apt-get update

Finally, the following installs a basic set of packages that should get you going with RMF:
sudo apt-get install ros-foxy-ament-cmake-catch2 ros-foxy-building-gazebo-plugins ros-foxy-building-map-msgs ros-foxy-building-map-tools ros-foxy-rmf-cmake-uncrustify ros-foxy-rmf-dispenser-msgs ros-foxy-rmf-door-msgs ros-foxy-rmf-fleet-adapter ros-foxy-rmf-fleet-msgs ros-foxy-rmf-lift-msgs ros-foxy-rmf-task-msgs ros-foxy-rmf-traffic-msgs ros-foxy-rmf-traffic-ros2 ros-foxy-rmf-traffic ros-foxy-rmf-utils ros-foxy-traffic-editor

But when running the first command, curl -s http://rmf.servehttp.com/repos.key | sudo apt-key add -, I get this error.

gpg: no valid OpenPGP data found.

Likewise, running basic curl to get the key curl http://rmf.servehttp.com/repos.key returns

curl: (7) Failed to connect to rmf.servehttp.com port 80: Connection refused

Consequently, running sudo apt-get update has some error and sudo apt-get install ... returns package not found.

Some info that might be useful, I'm using Ubuntu 20.04. ROS is inside docker container with image pulled from osrf/ros/foxy-desktop-focal.

Any help would be appreciated, thanks!

Start with the linked RMF installation tutorial and reproduce the repository-key and apt commands on Ubuntu 20.04 with the reported ROS Docker setup. Check whether the referenced key and package repository are available, then update the installation guidance so the documented commands work or clearly direct users to the supported source.