I did it, from the previous version.
- Copy the TWRP 3.6 zip to your phone
- Reboot to TWRP
- Flash the new recovery TWRP 3.6 zip
- Flash Magisk
- Clear dalvik cache
- Reboot to recovery and check if you noticed the new login "pad" then you're running now the new TWRP 3.6
- Reboot to system and enjoy.