How to connect Apple AirPods Max to Avantree transmitters and dongles?

Connecting your AirPods Max to Avantree bluetooth transmitter:

Step 1: Turn OFF the Bluetooth on every device that's previously connected to your AirPods Max.

Step 2: Get Airpods Max to Pairing Mode

Press and hold the noise control button until the status light flashes white.

Step 3: Get Avantree Transmitter into Pairing Mode as well
Please refer to its user guide if you're not sure how. With both devices in pairing mode, keep them close to each other and give them a few seconds. Please check their respective LED indicators to make sure that they've connected.

If no luck to get them paired, please Factory Reset/Clear Pairing History on both devices and try again. 
How to Factory Reset APPLE AirPods Max