Default HTC Sync manager and CDC serial

Hello, xda members!

I am complete noob in this, I bought my first smartphone several weeks ago and it's One M8

I've installed the latest Sync manager and tried to sync my phone, but, when installing drivers, windows couldn't find CDC serial, so Sync manager couldn't recognize my phone. HTC Support told me to reinstall Sync manager (while turning off firewall ad antivirus) and try again. Didn't help...
What should I do?

Thank you