The Passcode screen is a security verification screen that appears after the user signs in and reaches the Home page.
This screen asks the user to confirm their identity by entering one of the following:

Screen- TFA/Passcode

Passcode Verification Screen
Click on the Settings icon available in the left navigation bar.
Under My Account, select Two Factor Authentication.
Toggle the Passcode switch to ON.
Once enabled, an Enable Passcode popup appears.
In the popup:
Click Save to activate the passcode.