In order to be able to use the Ephemeris content you must first set up an Unsplash account.
Go to the "Settings" tab.
Click on "Accounts" and the "Connect account" button:
Add an account name and select Unsplash:
Click on "Next".
You must then log in with an Unsplash account (if you don't have an account you can create one by clicking on "Join" :
Click on "Save":