Microsoft Edge Home Page
  1. Make sure the below path exist under group policy by clicking on edit in the group policy object.
    • Computer Configuration > Administrative Templates > Windows Components > Microsoft Edge > Configure Start Pages
  2. If the above path doesn’t exist then follow below steps otherwise move to step 8.
  3. Download latest ADMX files from Microsoft (Administrative Templates (.admx) for Windows 10 Fall Creators Update (1709) )
  4. Install the MSI file in local system which will extract ADMX files to C:\Program Files (x86)\Microsoft Group Policy\
  5. Make sure the below central policy store path exists in domain controller where group policy editor is configured.
    • \\contoso.com\SYSVOL\contoso.com\policies\PolicyDefinitions
  6. If it exists copy the file MicrosoftEdge.admx to \\contoso.com\SYSVOL\contoso.com\policies\PolicyDefinitions
  7. Then copy the file MicrosoftEdge.adml to \\contoso.com\SYSVOL\contoso.com\policies\PolicyDefinitions\en-US
  8. After that, you should be able to configure Microsoft Edge start pages by navigating to:Computer Configuration > Administrative Templates > Windows Components > Microsoft Edge > Configure Start Pages

9. If your stuck at step 5 locating the path then follow the below

10. Make sure the path C:\Windows\PolicyDefinitions exist.

11. Then copy the file MicrosoftEdge.admx to C:\Windows\PolicyDefinitions

12. Copy the file MicrosoftEdge.adml to C:\Windows\PolicyDefinitions\en-US

13. Then Move to Step 8 above to configure the home page in Microsoft Edge.

Reference : https://social.technet.microsoft.com/Forums/en-US/9aaebca7-ffb4-4eae-86d5-15f99a18fef0/how-to-set-internet-explorer-amp-edge-home-page-via-gpo?forum=winserverGP