Skype for Business, Exchange delegates automatically appear in Skype for Business but do not have delegate abilities
Delegates show up in Skype for Business client but they do not have any delegate abilities or delegates show up that I have not added.
Delegates set-up in Exchange using Outlook Web Access or Outlook automatically appear in the Skype for Business client but they do NOT actually have delegate abilities in Skype for Business. The person for whom you need delegate access will need to set this up through Skype for Business.
Instructions on how to do this can be found at Skype for Business, Adding a Delegate .