Linux, WSL or Mac
Install pre-built GSI from here: https://t.me/OfficialOriginGSI
git clone --recurse-submodules https://github.com/origingsi/OriginGSItool
cd OriginGSItool
bash setup.sh
Example: for making OxygenOS of oneplus 7 pro firmware, you can use this command
./url2GSI.sh https://oxygenos.oneplus.net/OnePlus7ProOxygen_21.O.07_OTA_007_all_1905120542_fc480574576b4843.zip OxygenOS
check url2GSI.sh for more info