This is so funny, it seems that you are not a C++person who understands programming. As of now, most programs compiled by any compiler will erroneously report viruses, including the Olympia client, and sometimes be falsely reported by antivirus software.
The solution is to add Microsoft's digital signature, which costs over $800 per year. Even higher. HB is very old, no one would be willing to spend this money.
If you are concerned, you can use a virtual machine to run the client. Check the game
I can use AnyDesk remote desktop to demonstrate the process of compiling source code for you