Involvement
After talking to him, the party can learn the Mapping Room is just beyond the doors behind him. He will not let the party pass unless they have received permission from Mirie at the front desk. The party can then try a bunch of options to get past him:
DC 25 Deception check - Convince Morann you've already received permission
DC 20 Persuasion check - Convince Morann it's easier to just let you pass
DC 20 Intimidation check - Claim that Morann will soon be no longer standing