Kiosk Mode enables your device to run as a single-app kiosk for ScreenCloud, which should start the ScreenCloud app at boot without the need to either manually click the app or log into the device. However, if you're coming across a login screen or a pairing screen after setting up the device in Kiosk Mode then please review the following settings in your Google Admin console as displayed below.
The User Data setting under Device Sign-in Settings
1. Under the Device Settings, there is a setting called User Data (Erase all local user info, settings, and state after each sign-out). If you have this set to Erase all local user data, this could be causing your issue.
2. Please change it to Do not erase all local user data, this should fix the issue. This link should take you to where you can change these settings. Otherwise, follow the steps from this Google support article.
Power management on the sign-in screen: make sure the setting is switched to Do not allow the device to sleep/shutdown when idle.
Please make sure you're under the correct Organization or Sub-Organization in your Chrome Management Console. Adjusting these settings should help remove the login screen or the pairing screen upon starting your Chrome device in Kiosk Mode. If you're still having any trouble after trying the above steps you may want to refer to a more advanced article on How to Reset Your Chrome Device's Kiosk Settings and Chrome Enterprise Organizational Settings.