You get several options how to deal with the situation.
If you didn't kill Embeth Travelers, but proclaimed yourself a winner instead you won't have [Diplomacy] option (bug) and (Chaotic Evil) option.
Passing the Bluff DC 35 check (+3840xp) will cause the hunters to go away.
Passing the (Lawful Good) Diplomacy DC 35 check allows a choice between paying 3000 or fighting Ferocious Wyvern.
Failing the [Bluff] check, failing [Diplomacy] check, picking (Chaotic Neutral) option, picking (Chaotic Evil) option, or telling hunters to back off results in combat with Ferocious Wyvern.