No still wet behind the ears West Marine associate will know anything about NAVnet VX2. But... Furuno service will and they will actually still help you with this long obsoleted system. So look up their tech service phone number and call for help.
For now, the VX2 units were factory set for CMAP or Navionics, but not both. Which do you have?
VX2 upgrades have been released over the years and some were required to take advantage of the WIDE map formats. Check your VX2 firmware version and plan to upgrade if needed. I think the last update is 195002404.03 (might be different if CMAP or NAVIONICS, can't recall). Furuno will provide you links to software and instructions for upgrade.
VX2 SD cards are limited to 2 GB max if I recall.
Even if you update firmware and have the correct map type, you may still not be able to load the newest maps. I think my maps are from 2010 or so at the latest.