Using Outlook for iOS in business environments for email and scheduling
Have you enabled two-step authentication for your Hotmail account and are trying to add the account to the default email app on your Android phone? If so, you may be prompted to use a dedicated app password. If you haven't used a dedicated app password or have entered an incorrect one, you may receive error messages such as "cannot sign in as...".
Therefore, if you have enabled two-step authentication for your Hotmail account, make sure to use a dedicated app password to add the account to your Android phone. Please refer to this page for specific instructions: Manage app passwords for two-step verification - Microsoft Support.
Additionally, if you have entered the correct dedicated app password, please check your network connection. Sometimes, unstable network connections can also prevent you from logging in to your email account. You can try switching to a different network, such as your mobile network, if you are currently using WiFi.