Ok first thing------ YOU only need to ask the Question ONCE in the forum. Not in every section of the forum. And when someone can help you they will. Now your problem could be a number of things. 1- game services not set up properly. 2- incorrect ids entered. You need to go through your set up and double check in developer console and game services that you have set up all requirements. Then double check your ids, that they are correct. Hopefully some one can help out more.
Have you actually set up Leaderboards and achievements in Google Play? BB doesn't do achievements but you must have them to publish your leaderboard. Make sure that your Google Play licence key is correct - no spaces at the end of the final digital - same for leaderboard and Game services ID.
Login should be automatic once you've set stuff up, but you need to add a button for people to view the leaderboard.