Installing custom ROM in Android studio AVD

It is very unlikely that regular custom ROMs will work in the emulator:

For the android emulator special device drivers like display and other fake drivers/services (e.g. for telephone, GPS with is usable but there is no GPS chip) are needed. Regular custom ROMS don't contain those drivers and therefore can't be loaded in the emulator.

If you want an adapted ROM for the emulator you need an image that bases on the AOSP emulator image.