Help needed to get the app ownership shifted to administrator

One of my former employee created an app on Appsheet. After his exit we wanted to ensure that the app ownership is transferred to the administrator but when we try to access the appsheet page ( using former employee login credentials) the security is not allowing and asking to login from the former users browser or his home WIfi.

Any idea on how to resolve this issue

Was the account deleted and then recreated again? If that’s the case, then the authentication ID is different and you are not able to open the app. What is the exact error message when you have tried to open the app? Is the app shared to someone as “Edit definition” so you could copy the app to your account?