airport to Jemaa el-Fnaa by LOCAL bus? (Marrakech)

Hi everyone, I think here there are lot of local or local-like people looking so I give it a chance..

I know there is airport bus 19 from RAK airport to Jemaa el-Fnaa and they offer 30 MAD one way.

However: I like seeing lots of local sides and I wanna try the local bus. I heard there is a local bus which also goes to Jemaa el-Fnaa. Do you guys know which number? and how to find this bus?

Many thanks!