Into the future doesnt show in the worlds

nope there is no world in the list of worlds to play in the future world it is a sub hood (like world adventures and uni ) oasis landing is a sub hood you travel there , a time portal should appear on your lot if enough room or in the world your already playing in you send your sim to inspect the portal then emit appears he'll give you a small quest collect power cells you hand them to him  he fixes the portal which you then click on to travel to the future, if the portal did not appear in your world you can buy one in build/buy mode-transportation  

edit to add once you travel to the future world you can travel back to your home world anytime by going to the community center building where you arrive   there is another portal  click on that to return to the home world also you can actually if your sims have enough simoleons you can buy  a place to live there and with the into the future you can stay in the future world as long a you like 

( with world adventures and uni you can only stay there  in those worlds a set time )