Hi c4dmac, thanks for following up here.
With regard to the issue you've reported you can get fixed by reestablishing the executable bit on the kernel_app file found in the zip archive.
To sum it up, upon downloading the project tool archive you have to:
remove quarantine
xattr -d "com.apple.quarantine" ./cinema4d_r21_project_tool_20190903.zip
extract the archive (either via terminal or via finder)
unzip -d ./cinema4d_r21_project_tool_20190903 ./cinema4d_r21_project_tool_20190903.zip
re-establish the kernel_app executable bit
chmod 555 ./cinema4d_r21_project_tool_20190903/kernel_app.app/Contents/MacOS/kernel_app
Best, Riccardo
