Assuming you are talking about the ROM zip, did you verify if the zip file hash matches what is mentioned in the download site?I spent all day finding ways to solve this problem: "Invalid zip file format." But I'm unable to resolve.
I downloaded ADB from android developers,
the latest version of Xiaomi USB driver,
TWRP, ROM, and Gapps files from here.
Because of the error message I mentioned before,
I exactly followed steps from down here.
"Fix TWRP Invalid Zip File Format Issue - Tech Gearz"
I really like the features of the firmware that you made.
I hope you could reply as soon as possible
For Havoc-OS-v2.8-20190826-clover-Official.zip, the hashes mentioned are:
SHA1:
a050b6842446cc303d19dc5e3ec395caa30e77dd
MD5:
fc23d002dfe09669fe34ec37e231505f