The keys tell you exactly what is wrong. Match what you see:

SIMHUB AUTHENTICATION, with a crossed out account icon. SimHub is not running, the DNR plugin is not loaded, or no DNR account is signed in. It is also what you see if the deck cannot reach SimHub at all. Start SimHub and sign in on the plugin's Home page.

MEMBERSHIP REQUIRED, with a padlock in DNR orange. You are signed in, but your membership does not include the deck app. Control Decks need Team Driver or above.

Choose Toggle, Choose a Colour, Choose Action, Choose a Read-out, Set a Hotkey or Add an Image. The key has not been configured yet. Open its settings and pick something.

DNR DIAL / SET UP on a dial. Same thing: pick a Control or a Display.

A value showing a dash. There is no live data for that read-out right now, because you are not in a session or the sim does not report it. Not a fault.

A dial reading iRacing. That control only works with iRacing running.

The deck flashes its own warning when you press a key. The action could not be sent: SimHub is unreachable, the membership does not cover it, iRacing is not the running sim, or a race director key has no car number set.

In SimHub, the Control Decks page says No deck software found on this PC if the manufacturer's own software is missing, and NO DECK CONNECTED if the software is there but nothing is plugged in. Settings you change while nothing is connected are still saved and apply as soon as a deck appears.