You just need to set a 16 character key for the EncryptionKey constant in the Encryption module in the App Store modules folder of your Project.
You can do this locally by setting it in the module (not recommended), or by going into your Settings, editing the current configuration, selecting the Constants tab, and clicking New. You should then be able to find the constant and set it.
When you deploy, it will be in your Constants settings for the Environment.
Hope this helps
I have set up the Encryption key. After Completing that I am able to do Server configuration.
In Your encryption appstore module you have a constant Encryption Key ,You have to add a key and the length of this key must be 16 characters as required and you will be good to go.