Flashing process
Arijit Saha [ #DARK_ELIXIR® ]™Reboot to recovery
Wipe partition
Flash ROM
Format data ( you can try without it )
Reboot
Complete setup wizard
Then boot in to recovery
Flash magisk 20.3 or 20.4 :- here
Reboot
Flash magisk gapps on magisk :- gapps
Reboot
Install play store apk normally :- apk