If ur phone is ab or a only ,and ur phone is ship with android 9 ,make sure u use vndklite vanilla,and make sure u know it phone architecture like arm64 86-64 which is for 64bit .when u are trough downloading and extracting, boot to TWRP ,wipe cache,system,data ,darvich and cache ,back to menu of TWRP select install tap install image and select ur extracted havock image and flash to system partitions.and rebook to recovery first (ignore no OS installed message)and now reboot to system
