Depending on your eligibility, you may have access to Microsoft 365 ProPlus, which allows the installation of subscription-based versions of Office apps such as Word, PowerPoint, Excel, Outlook, Teams and OneDrive.
Please confirm your Microsoft 365 ProPlus access eligibility by consulting this article: Microsoft 365 Licensing – Toolkit overview and eligibility.
Note: If you have another account set up on your phone (such as a Hotmail account), you may need to reset the Microsoft app to clear other credentials it may have stored before you can sign in with your UTmail+ account.