There are lots of people having issues with the HTC app to sync the phone with Outlook etc, the new installer has many bugs :/
Here is a quick work around:
Install HTC Sync, but when it pops-up and says the HTC Driver Installer failed, do not press OK or Cancel, but instead use Windows Explorer to search your User or TEMP directory (usually under \Users\or C:\Users\yourname\AppData\Local\Temp) for “HTC”. It should find a file called HTCDriverInstaller.exe. Copy this file to a new directory, then cancel out of the HTC Sync install.
The files may also be inside a folder with lots of letters and numbers in it, like this 578F69EC-8162-4866-A0C9-CCC2669C4CF7 – Just have a look around, it IS there!
Now run HTCDriverInstaller.exe. It will fail as well but, again, do not press OK or Cancel yet. Use Windows Explorer to search your User or TEMP directory again for “HTC”, and this time you should find a file called HTCDriver.msi. Copy this file to a new directory, then cancel out of the HTCDriverInstaller install. You may also delete the HTCDriverInstaller.exe file at this point.
Now run HTCDriver.msi, and it should successfully install the drivers. Save this file in case you need it again in the future.
Restart the HTC Sync install, and it should see the drivers are already installed and so proceed directly to install the HTC Sync software.
Hope this helps!