There are several things that come along with live rock.
The bacteria on the LR is the basis for its use as a biological filter. No need for light.
Coralline algae also helps to consume nutrients, and covers the rock to prevent the spread of nuisance algae. Some light needed, but not very intense. Keeping Ca and alkalinity up help it spread.
Both of the above are found on all rock that is truly live.
The following are more like bonuses, found on some live rock, but not all.
Macroalgae. They're pretty and help with biofiltration to a small extent. These need significantly more light than you have.
Sponges. Amazingly enough, some survive shipping, and can be excellent biofilters. Or some simply die. Some can make use of light, others do not need or want light.
Corals can come along as well. Many need a good bit of light, others don't need light at all.
Anyway, you will get most of the benefits of live rock even with low light. It wouldn't be worth spending a lot of money on fancy rock with cool corals and macroalgae, though.
