Do I have to install both for spoofing? I didn't deinstall playstore/services first. After booting screen flickers, so I did something wrong.
Since the patch is made by modifying the services.jar directly and outside the ROM (the ADB part is just to connect and pull the file from the file system, it doesn't do anything to the ROM yet), it shouldn't matter if you have already flashed Nandroid or not.
I recommend you to do the procedure of that thread first, but only flash the spoofing patch after you have installed Nandroid, because it'll handle clearing play services out of your ROM.
And, fyi, you don't need to flash the microG\_AVDx86api30\_magiskMaRViN.zip. This is a microG package but you'll use Nandroid instead, so microG\_AVDx86api30\_magiskMaRViN.zip not needed.
In short: create the patch following the tutorial from the link -> flash Magisk (if your ROM doesn't have it) -> flash Nandroid from this thread -> flash the spoofing patch.