Step 1: Click the blue "Get Started" button to go to the next screen. (This screen may show up when you open the latest version of Inky for iPhone, you may be logged out automatically. If you are, or if you use "forget credentials" at some point, when you start Inky you will see a new screen as shown below - you should always click Get Started.)
Step 2: on the next screen, look in the bottom right corner and click the "Legacy Sign In" button which will take you to the final screen and Step 3. (There is a Sign In button for Microsoft Office 365 accounts. Do not use this button unless you have arranged for a new type of Inky account with us.)
Step 3: Log in with your existing Inky username and password as you normally do using the final screen shown below.