Before you can use your Chrome OS player, you need to prepare the Google domain on which you are going to embed it.
Indeed, each Chrome OS player is linked to a Google domain so that you can monitor it and administer the various settings remotely from the Google Admin console.
Create an Organisation Unit
You will have to create a OU dedicated to the dynamic display Chromeboxes. This OU will be set in Kiosk mode to automatically launch the Comeen Play application when the player is booted.
Kiosk mode setup
In your Admin console, go to Devices > Chrome > App and Extensions > Kiosk (direct url: https://admin.google.com/ac/chrome/apps/kiosk)
Select the organizational unit created above.
Click on the "+" button at the bottom right
Select "Add from Chrome Web Store"
Search "DynamicScreen" then click on "Select"
Then set this application to automatic launch mode:
Chromeboxes enrolled in this organizational unit will now launch the Comeen Play application in kiosk mode!