Here's how to unlock the next stage of Pengle
To get keys, go to the set of 3 keys on the map and click on them.
Inside you will find 3 locks across the top and 2 boxes at the bottom. Click on one of the 3 locks.
A listing of all your friends will appear.
You will see, near the top left corner, "All Friends" with a down arrow.
Click on the arrow and choose Pengle Players. Choose your Pengle friends that you want to send key requests to.
You can send up to 50 requests each time and you can send out as many times as you want.
The more requests you send, the quicker you will get all your keys but it's generally useless to send more than one request to each person unless you don't get a response within a few hours.
It also helps to message your close friends since they have to see the request before they can send you the key.
You need 3 keys from 3 different friends - you cannot get more than one key from each friend.
Your friends will see the key requests when they enter the app and simply click on the box to send a key back to you. When you enter the app you will see how many keys you have received and if you click on the 3 keys, you will see who sent you the keys.
If you are already in the app, you would have to refresh the page to update your keys.
Using this method, you will be sending only to your friends who play Pengle.