Once turned navigate to Admin > Users.
Once on the user’s tab click on the pencil icon next to the users record you would like to enable this for
Check the option 'Can add delivery' and then click save.
The user can then click onto the 'Add Delivery' icon next to each Purchase Order:
The user can then enter the delivery information like shown below:
Once the information has been entered and they click save this will show that the parts have been delivered: