Information on how to of a downloaded zip to ensure it hasn't been tampered with.
: If you already have an older TWRP, you can flash the .zip directly from the "Install" menu. twrp 3020 zip download repack
Developers use tools like the Carliv Image Kitchen to unpack a stock boot image and "repack" it with TWRP RAM disks for devices without a dedicated recovery partition. Information on how to of a downloaded zip