You are trying to install Symantec Endpoint Protection Cloud (SEPC) onto a workstation. You are able to select "Enroll now" but unable to download the SEPC_install.exe file. You are able to successfully download an installation package, but when you try to download the installer from the package, the download will hang at around 51% or stop at "calculating".
It is possible that only one workstation will present this issue while other workstations will download/install SEPC correctly within the same network.
"Error-Unable to Continue
An error report with no personally identifiable information is available to send to Symantec (recommended)."
A specific example is a SonicWall that is running "Capture ATP" on the network. This is known to cause the error above and prevent the download/installation half way through (normally at around 51%).
Simple work around is to download the installer package and install SEPC onto the machine through another network or through mobile data.