Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Two versions of Outlook cannot coexist on the same computer.
Try the following steps to resolve the issue:
1. Open the Run window (press Windows + R) then copy and paste the path given below and press Enter
2. C:\Program Files
3. Right click on the folder Microsoft Office and select Rename. Rename it to Microsoft Office.old
4. Ensure no version of Microsoft Office is installed on the computer
A If you find any version of Office listed in the Programs and Features list, repair the existing installation using the disc or the downloaded setup file.
B Once the repair is complete uninstall Microsoft Office.
5. Try to install Microsoft Office 2003