Actually, illegals can only get an AB 60 license (for non citizens) which doesn’t automatically register them to vote.
However, according to https://www.sos.ca.gov/elections/voting-resources/voting-california/registering-vote
“The voter registration application asks for your driver license or California identification card number, or you can use the last four numbers on your Social Security card. If you do not have a driver license, California identification card or Social Security card, you may leave that space blank. Your county elections official will assign a number to you that will be used to identify you as a voter.”
This seems to indicate that illegals *can* register to vote in CA without an ID. No wonder Dem politicians in CA don’t want voter ID laws. It would prevent all these people who registered to vote without an ID from voting, most of which vote Democrat.