No add user option in android marshmallow moto e3 power It's been a  while I tried few options also but not able to find how to add user in marshmallow is not present in settings any way to debug this or to get activated as marshmallow supports multi users.
Your device does not support multi user mode

See reply by Senior Moderator in Lenovo forums


  There are many features that are disabled on different phones due to hardware or other reasons. It could be that the GPU can't handle this. It could be that some features are reserved for mid or high end phones. 
  
  Another example is multi-user mode


(Emphasis supplied)

Sorry about that !



On supported Moto devices, you find this option under


Settings &rarr; Device &rarr; users &rarr; add user
Another way to find out is to use the search option in settings ( magnifying glass symbol on top right). Just typing  add brings up this option, as you can see in first Screenshot
From the notification bar, it has a user icon at extreme right, clicking on which will give you user options , as in second screenshot