Login to the application with your username/ domain name and Microsoft Office 365/ system's password.
Please follow below steps to check your username:
Windows OS:
Press Windows + R to open "Run" box.
Type "cmd" and then click "OK" to open a regular Command Prompt.
Type "whoami" and press Enter. You will get your username from this.
E.g. nagarro\vishalkumar. Your username will be vishalkumar
Mac OS:
Open the Apple launch pad
Click on Terminal application
User will be shown the username or domain name. e.g. vishalkumar