Issue on installing requirements on Mac

I am following Getting Started Assistant on Mac platform.

However, I run into an error when I issue: "pip3 install --user -r zephyr/scripts/requirements.txt ".

ERROR: Could not find a version that satisfies the requirement hub==2.0 (from -r zephyr/scripts/requirements.txt (line 10)) (from versions: 0.0.1)

ERROR: No matching distribution found for hub==2.0 (from -r zephyr/scripts/requirements.txt (line 10))"

Any ideas?

Thanks

Zhenchuan