User guide
You can use public instance on: fos.robotx.su
If you want to use self-hosted solution, read developer's guide. In this guide we will use public instance, so all links will be with https://fos.robotx.su/rdui base path.
You can open RDUI with GET parameter: robot_host. For example, you have robot with IP (You have to be in same network with robot or robot have white IP with port forwarding): 192.168.0.20 and http_api on this robot works on port 8080, so you can open next page:
https://fos.robotx.su/rdui?robot_host=192.168.0.20:8080
Open RDUI Settings page from menu, or direct link: https://fos.robotx.su/rdui/settings
Next insert robot host in Robot host (ip:port) field and press Save button.