Congrats, Pathfinder, you’ve carved out a home for the Milky Way species in Andromeda and put a halt to the Archon’s scheme to exalt the entire cluster. Your work isn’t necessarily over yet, however, as there are still sidequests you can complete (basically everything that didn’t involve the Hyperion), vaults to activate, planets to terraform and all that other business you may have neglected.
After the credits the Ryder siblings will chat in Ryder’s room in Meridian. When done, head outside and you’ll be ambushed by the leaders of the Initiative, who are naturally haggling over politics. Unfortunately, the call to name an interim ambassador falls on you. Make your choice (the options vary based upon what quests you’ve done, and what choices you’ve made) after which explore the Hyperion, whose layout should be familiar. Chat with your crew members and other characters you may have met and helped on your travels (again, variable based on your actions) and enjoy a teaser about the Quarian Ark. Once done, return to the Tempest and continue your adventures.