Once the ROM finishes flashing, return to the Install menu, select the .zip file, and flash it (skip this step if your ROM has Google apps pre-installed). Tap Reboot System .
A clean flash is essential to avoid conflicts. In TWRP, go to Wipe -> Advanced Wipe and select Dalvik / ART Cache , System , Data , and Cache . Then swipe to wipe.
Unofficial builds often bring the device up to Android 11, 12, or 13, versions it never officially received. Performance Optimization: Pixel Experience