Here are the instructions on how to create an App password for Nexus365.
If you have MFA enabled and an app isn't prompting you to enter a security code when you sign in, you may be able to sign in with an App password instead. An App password is a long, randomly generated password that you provide only once instead of your regular password when signing into an app or device that doesn't support MFA.
You only need to create an App password if you have MFA turned on and are using an app that doesn't support it.
To enable App password for a personal or generic/secondary email account please use the App Password Enablement – Multi-Factor Authentication (MFA) service request.
Things to Know about App passwords
• You should create a separate App password for each device that requires one.
• The same App password can be used for multiple applications on the same device.
• Once an App password is created, there is no way to go back and get the value. You must create a new App password and delete the old one.
• If an account becomes compromised, it is a standard operating procedure to clear all App passwords.
• Never install an App password on a device you do not have complete control over.
If exposed, App passwords are dangerous as they bypass the account password and MFA. Keep them in a safe place until you have them safely configured on the device.