Entire data vanishes in step number 1, so take backup.1) Wipe dalvik, cache, system, data in TWRP and Format Data is up to u-where u hv to type "yes". (just to be safe)2) Since 23rd march '20 build, the Firmware is shipped together with the ROM so u dont need to flash firmware (if u r installing older versions, u need to flash firmware)3) Flash the PE / Plus ROM through TWRP4) Restart5) Successful boot means u can flash magisku can either:-Use built-in OTA app, that is, settings-system-system update-check for update-downloador-download the incremental package from here and flash it in TWRP.