Hi,
I am trying to use the apex autorigbuilder with the addgroom node and I cannot get it to work.
In the sceneanimate state, the hair does not follow the rig.
I attached a screenshot and a minimal Scene.
I tried with 21.0.499

You were pretty close, just missing 2 crucial steps. Please log a bug with your hip file for some better error reporting.
I've attached the 2 fixes I made to it.