This information is condensed from the CronusMax User Manual. The relevant section can be found here, but this should be enough to get you started. This method is called Manual Authorization and requires only the CronusMax between the QuadStick and the game console. A second optional method called Auto Authorization, that eliminates the need to connect and disconnect the authorizing controller before connecting the QuadStick, but needs additional hardware, is described here.
Connect the CronusMAX PLUS to your XBox One
Remove any Xbox One Controller Batteries
Remove any batteries or charger pack from your Xbox One Controller (if it has them).
This is a very important step or the controllers will not authorize correctly.
Connect your Xbox One Controller to the CronusMAX PLUS
After a couple of seconds the display on the CronusMAX LED will go from the Authentication 'AU' Animation to 0 (or a number if slot recall is enabled and a script was previously loaded). If the Display does not change from showing AU, try a different Micro-USB Cable between the CronusMAX PLUS and Xbox One Controller, and/or physically power cycle your Xbox One.
If the LED on the CronusMAX PLUS does not change from AU to a number then the authorization controller is not authenticating. 9/10 this means the Micro-USB cable to the controller is faulty or not full data or simply not compatible, you should try another one. Also make sure the controller is powered on.
Disconnect your Xbox One controller from the CronusMAX PLUS
Once the display on the CronusMAX PLUS shows a number, disconnect your Xbox One controller from the CronusMAX PLUS.
The CronusMAX PLUS LED Display will now show the spinning Standby animation.
Connect your QuadStick to the CronusMAX PLUS
Connect your QuadStick into the Input Port of the CronusMAX PLUS.
Your system should be ready to use
After a couple of seconds the display on the CronusMAX LED will go from the spinning Standby Animation to 0 (or a number if slot recall is enabled and a script was previously loaded) - indicating that the controllers are authorized and you're ready to play.