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".
"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%).
It is possible that only one workstation will present this issue while other workstations will download/install SEPC correctly within the same network.
Simple work around is to download the installer package and install SEPC onto the machine through another network or through mobile data.
Another solution is to whitelist the required SEPC ports/domains on the external firewall. These can be found in the article Required URLs for Symantec Endpoint Protection Cloud.