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
Sorry about that !
On supported Moto devices, you find this option under
Settings → Device → users → 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