"Open console" needs to open a network connection to a port > 5899 (like 5900, 5901, 5902, ...) of one of the flexVDI Hosts (the one that is running this virtual machine).
If the guest console window is not opened in a few seconds, check that there is network connectivity from your local machine to those ports in the physical host.
The guest tools
flexVDI offers the flexVDI Guest Tools. This software significantly improves the user experience providing features and improved performance. When you complete the installation of the O.S, with your machine still running, you can right click on the Guest in flexVDI Dashboard, and then click on the "Insert Tools" command. A dialog will offer you to select a virtual optical drive where to insert the guest tools ISO image; if the drive is in use by another image, they will be swapped. This will insert a virtual optical disk in the machine that will start the installation of the software. Alternatively, you can download the latest version of the software from http://depot.flexvdi.com/guest-tools/