So after countless tries, finally got the achievement to unlock today, on my first try with these precautions. This is how I did it(with the help of others):
-Create a Facebook account with the same email as your Microsoft account if you haven't already.
1.Log in to the desktop or mobile site of Facebook(not the app). Go to account settings, then to general settings, email adress and deselect "use your facebook email"
2. Go back to the account settings and then go to apps. Here delete "Make in the world".
3. Have Facebook app installed.
4. Have the latest "What in the World?" update installed.
5. Start What in the World?, select a puzzle you haven't completed. Select the shopping cart in the top right hand corner. Select connect to Facebook.
6. Fill in your email and password if you're not logged in yet, and give the app the 3 functions it asks for. Your phone returns to What in the World? and the achievement unlocks.