You can still flash this ROM from TWRP too, however, the OP recommended to use adb sideload with the given crDroid/Lineage recovery. He has added TWRP flashing support in recent builds I think, but you have to try on your own risk.In TWRP you could (in the past at least) flash zips without a computer. I've been off from modding for a while so I don't know if something's changed.
With ANDROID 7.0 and later, there is a new partition scheme, A/B partition. More on this here. On that scheme, dedicated recovery partition is not needed and the whole idea of recovery is becoming (or has almost become) redundant.