Is kundalini awakening a requisit to Harvest?

[jivatman]

Yes.
...
4th density harvest is simply when the kundalini serpent has reached the heart chakra or energy center (and become seated there more or less stably).

But if the majority of Wanderers aren't aware they are Wanderers, doesn't that mean that they are inactivated and will have to repeat third density??

Highly unlikely so many would continue to volunteer for third density if the majority of such became karmically involved.