Hi Sadr,
This is usually an indication of some kind of firewall or security issue. You can confirm this by trying on another computer within your institution and then trying again on a home computer. Or, if you have a laptop, you could try connected to your institutional network and then some other form of private network (home or WiFi somewhere).

If this turns out to be a network issue and not one of just your computer configuration, then you can either upgrade connected to a different network, or you can use one of the disconnected installers for Skyline ("unplugged" or "administrator"), remembering that this will require you to upgrade manually in the future.

If instead you determine that other computers on your network can install 3.7 without failing to download Skyline.exe, then you should refer to the Tip page on "Recovering from a Broken Installation":

https://skyline.ms/install_recover.url

Hope this helps. Thanks for putting the time into upgrading to 3.7.

--Brendan