Was having the same problem, but was updating instead of installing.
I changed GW2.exe’s Compatability settings to “Always Run As Administrator” and everything worked fine after that.
Not sure if it was just a coincidence or not, but the connectivity sticky does mention setting GW2.exe to “Always Run As Administrator” so you might want to try that.
-edit- By “work fine” I mean I don’t get stuck at 0.0 KB/s any more. The servers seem to be very slow. I’m getting about anywhere from 7 KB/s to 70 KB/s. I have a 25mbps/25mbps fiber connection, so I should be able to get up to get up to 25,600 KB/s, theoretically, but easily near a MB/s in real-world settings, not the 50 KB/s I’m now getting.