The group should be left blank.
The hostname should be just an FQDN. e,g.
countrya.dynamic-m.com
I'm not 100% sure with OGS, but I think you just list all the servers it can choose from. The last one I did was a bit more complicated with trusted network detection, and I can't quite remember which bits were only for OGS.
Also note this:
"OGS location entries are cached for 14 days."
So if you connect from an IP address, you will continue to connect to the same AnyConnect head end if you use that same IP address for the next 14 days.
You might want to test this using something like a 4G connection where you can disconnect/connect again to get a different IP address for each connection.