In the installation procedure, at the point number 6 ("Change to alternative slot"), i have toot reboot the phone or i have just to selection the alternative slot?
1. Boot in to twrp
2. Flash The ROM zip
3. Flash Twrp installer zip
4. Tap on reboot and tap on recovery
5. Now your phone reboots to Twrp again
6. Change to alternative slot
7. Flash gapps ( if rom doesn't comes with gapps )
8. Flash magisk
9. Reboot system
10. Wait for 6 min
11. Congratulations you have been successfully installed custom ROM on your Nokia 6.1 plus .