In addition to the previous post, oVirt requires you to use a DNS entry, not an IP address to access the web interface. If you don't run your own DNS server, you can simply edit the host files on the client PCs. This is quite easy to do. For example, just Google "edit host file on Windows".
Did you add the vnic after the installation? The Linux distros are pretty good when doing the install of detecting the NICs, but if you add them later you may have to enable them afterwards. Try running "sudo nmtui" and see if you can enable it that way. Otherwise you will Need to activate it manually.
Lastly, windows was tricky for me at first. Have you downloaded the oVirt driver ISO? Make sure that you have downloaded this and have it available for oVirt vms to use. During the windows install, you will have to use the "change disk" or "change CD" button in the console once you get to the point where you can choose your driver's, load the correct drivers, and then switch back to the windows iso and continue the install.
I hope this helps! Once I am next to a computer I can answer more fully if necessary