Error 1905 failed to register happens when the installer can not register the Impact add-on for Microsoft word. This Word add-on is required to customize your templates.
There are two option to correct this registration issue;
1) Using Impact un-register then re-register the Word add-on. Read More
2) Re-run the downloaded installer in administrator mode. Right-click on the installer icon and select "Run as administrator' from the popup menu.