Office Pro Plus 2021 only support Office Deployment Tool (ODT). To install the new Office 2021:

1. Download the latest ODT from Microsoft Download Office Deployment Tool from Official Microsoft Download Center

2. Extract the ODT files where you want them. Eg, C:\temp\Office2021

3. Run Powershell with elevated permission as below

> .\Setup.exe /configure .\configuration-Office2021Enterprise.XML