you need to extract the boot.img, patch it with Magisk Manager, and flash with fastboot. THERE IS NO WORKING TWRP AS OF YET.Can you tell us which steps? I wanted to keep TWRP and Root out of the last stable.
*****USE AT YOUR OWN RISK*****
*****I AM NOT RESPONSIBLE FOR YOU SCREWING UP YOUR DEVICE!*****
IF YOU'RE NOT FAMILIAR WITH FASTBOOT, LEARN OR MOVE ON
I've done the hard part... Download the patched boot image below.
Command in terminal - fastboot flash boot patched_boot.img