First, make sure you have an Android build environment and the repo tool set up. After that, run the following commands:
repo init -u https://github.com/ProtonPlus-ORG/manifest -b tm-qpr3
repo sync -j$(nproc --all) --force-sync --no-tags --no-clone-bundle --prune --optimized-fetch
source build/envsetup.sh
lunch device-buildtype
m otapackage
This is a large download that will take approximately 100 GB of disk space, so plan accordingly.
Good luck!