Additionally, I am on T-Mobile firmwareUsed the top Magisk AA in the 1st page. Booted to bootloader with adb. Then "fastboot reboot (Magisk patched boot image but use original file name) that boots you into temporary boot of phone. Once phone is booted up, install latest Magisk Manager, start the app then tap on the upper right corner install, then select direct install. Reboot and you are done. Read how to keep root for OTA updates.