Optical navigation would be more than sufficient. Images of the Moon and the Earth against key stars, a clock, and a computer is all you need. Apollo had such a system as a backup, which was used to verify the ground tracking results.

This is the Apollo sextant:

[![Apollo sextant][1]][1]

The definition of "autonomous" in the document is:

> Autonomous: Ability of a space system to perform operations
> independent from any Earth-based systems. This includes no
> communication with, or real-time support from, mission control or
> other Earth systems.

So indeed the orbit determination would need to be possible using only on-board resources. Though you need to be able to _look_ at the Earth, so hopefully the Earth itself is not considered an Earth system.

  [1]: https://i.sstatic.net/5eD8X.jpg