The documentation links which explain how to install/deploy the V2110 virtual controller are located in GTAC Knowledge article
How to install V2110 in virtual environment.
But, where to locate and download the V2110 image needed for the virtual wireless controller install?
First, in order to see any of these files at the Portal download site for Extreme Wireless (formerly known as IdentiFi Wireless) Controllers (https://extremeportal.force.com/ExtrProductDetail?id=01t34000003w10tAAA) requires that your Portal account be associated with a service contract which includes coverage for one or more "WS-V2110-x-xxx" virtual controllers. If instead in the Software & Downloads section you see only notification message "Displaying resources you are entitled to. If you do not see the resource you need or are entitled to, contact GTAC.", then you will indeed need to open a case with the GTAC to resolve this - or to receive the necessary upgrade file(s) from GTAC - before the install can proceed.
If your Portal account does have the proper entitlement, then in the Software & Downloads section you'll see a list of firmware release file packages. Here is an example of what to look for, if seeking the latest (as of December 2017) 10.41 release:
V2110 Hyper-V v10.41.02.0014 Software 182.7 MB Maintenance 11/28/2017 [Hyper-V .ize upgrade (zipped)]
V2110 10.11.03.0004 OVA Image 358.3 MB Maintenance 11/28/2017 [VMware .ova install (native)]
V2110 v10.41.02.0014 Software 183.6 MB Maintenance 11/28/2017 [VMware .bge upgrade (zipped)]
V2110 Hyper-V 10.01.02.0038 ZIP 294.4 MB Maintenance 11/28/2017 [Hyper-V .vhd install (zipped)]
When you click one of these packages then click the Download File link to begin a package download, you will be asked to enter the serial number of the product for which you are downloading. A virtual controller has no serial number, so enter the intended controller Locking ID / Admin MAC value if known, otherwise enter 00-00-00-00-00-00.
After download, use the .vhd-containing zip file (Hyper-V) or native .ova file (VMware) for the initial install (if needed) of the WS-V2110 virtual controller, then use the unzipped .ize file (Hyper-V) or unzipped .bge file (VMware) to upgrade it to the desired release version.
Note that the .rize and .rbge variations on these files are Rescue Images, used only for recovery purpose (to a factory-default configuration if a user-configuration Rescue Image is for some reason not available).
It is always an excellent idea to review the release notes (from the web site's Release Notes section) before using any of these files.