Couple things could be going on here. first off Im assuming you're not running it in some virtual environment so few things you could try
The issue might be your CPU hardware, if you have like a core 2 duo processor or something along the low lines like that then it probably does not support Extended Page Tables and Unrestricted guest(thats your EPT + UG error) try running on an API lower than 21 and see if it works you will still get warnings but it should work if that the case
if that isn't the case see if intel virtualization technology is turn on in your bios
try updating your HAXM(hardware accelerated execution manager) on your computer using resource file from the official site(software.intel.com) or whatever it is
or if you don't even have HAXM you can try installing it....
Installation of Intel HAXM consists of two steps. First, you need to download it using SDK manager. Then you need to run intelhaxm-android.exe to install Intel HAXM
also would help to know what kind of processor/cpu you have