Unable to install custom ROM, missing options in recovery menu

> In recovery, perform a full factory reset, wipe cache, dalvik cache > and wipe data/factory reset. (source: https://www.naldotech.com/how-to-install-custom-roms-on-nexus-6p-with-custom-recovery/) But in my Android Recovery I can only see following options: - Apply update from ADB (or SD card) - Wipe data/factory reset - Wipe cache partition - Mount /system - View recovery logs - Run graphics test No such thing as full factory reset, wipe cache, dalvik cache. There is also no "install" option. My Recovery screen says: Android Recovery, google/angler/angler, 8.1.0/OPM6. ...(long version), user/release-keys Prior to that I have installed custom recovery (TWRP) from Play Store. Perhaps TWRP should be installed differently?