Retarget manager and Retarget source

I am trying to follow the steps described here:

But in the step 3, where it says open retarget manager, instead I have retarget source. I try to add the skeleton I want to be the source, but I can’t seem to create the Humanoid Rig that the instructions describe. I am using the version 4.4.3. Can anyone help me with this?

Thanks in advance