[OFFICE.COM/SETUP] - Open a web browser (Chrome, Safari, Firefox, etc.) in the system and go to www.office.com/setup.
Click on the "Create a new account" option for the signup.
When prompted, give the details like name, date of birth, email address during the registration process.
Press the Submit button.
Microsoft Office sends an email. Go to the inbox and click on the link to complete the last lap of registration - [WWW.OFFICE.COM/SETUP]