RM3100 compass support

I am building a new antenna Tracker at the moment and I am using a Drotex M8N XL GPS+Compass module. But I would like to add a second Compass as reference and I tried to use several RM3100 compasses but none of them would be recognized.
Can someone integrate the support for it to AT firmware?

It is supported although you might have to jump on the latest version.

https://firmware.ardupilot.org/AntennaTracker/latest/

Sorry that was my fault. I installed the official version and there it seems not to be supported. Now it gets recognized! Thanks!

I tried to calibrate the RM3100 but I am not able to start calibration.Neither via the onboard Mag calibration button, nor via COMPASS_LEARN 3 setting.
Have you got an idea what to do?

make sure your disarmed, Tracker auto arms by default, you will have to maunaly disarm.

How can I disarm tracker?
edit: found it. Change the mode to STOP