As Linjo says, you have other software running on your server that is already using TCP port 80.
Remove this software or change its configuration to use a port that doesn't conflict. Rerun the Connection Server installer and then you won't get this error message.
To find out what the conflicting software is, run the command:
netstat -ano
This will list all the listening ports. Look for a TCP line with a local Address ending in ":80". Look at the PID value in the last column. e.g. if the PID value for the listener is 1234 then run the command:
wmic process list brief | find /i "1234"
This will show you the conflicting software for you to know what to uninstall.
Let us know what it was.
Note that you can't install View Connection Server on your vCenter Server.
Mark