Source Code issues (could not load file or assembly)

We purchased your app with the source codes and I am not able to compile the application. The following is the error I am getting. Can you please advise a solution to this issue.

Could not load file or assembly 'xxxxx.dll' or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)

Try opening the folder in Windows Explorer, right-click the DLL-file mentioned in the error message, choose "properties" and click "unblock". Should help. More info here:

Well I was able to get it to work but I had to remove the read-only attribute. Then it compiled. I then put the read-only attribute back on and it still compiled successfully. Odd?

That happens with files, downloaded from the internet, on the latest versions of Windows. Not odd, but absolutely non-obvious security feature.
Solving problems with on-premises version of Jitbit Helpdesk ticketing system