So I am attempting to fumble my way through this, though I don't know what I'm doing

I'm running Windows 10 64-bit. I've installed Microsoft Visual Studio Community 2019, opened the 'JedShivaMeter.sln' file, and let VS install another 7GB of resources that it needs. Then I see this screen:
I noticed the part at the top that says 'Release/Win32'. It needs to be x64, so I clicked on 'Configuration Manager...' from the 'Release' drop-down box. I get this window:
Under 'Platform' I selected '<New...>', then selected 'New platform/x64' and 'Copy settings from/<Empty>' (the other option is to copy from Win32). 'Create new solution platforms' is ticked. Since it's empty, I'm not expecting it to work, but I'm going back to the main window and selecting 'x64' in the drop-down. Then I right-click on 'Solution 'JedShivaMeter' (1 of 1 project) and select 'Build Solution'. Sure enough, it doesn't work; I get the following in the output window:
1>------ Build started: Project: JedShivaMeter, Configuration: Release x64 ------
1> Creating library E:\My Documents\OneDrive - Southern Cross University\Personal\RIDDUM\MDKPimPom\New 2017\iteration 03\JedShivaMeter code\jedshivameter-code-r16\x64\Release\JedShivaMeter.lib and object E:\My Documents\OneDrive - Southern Cross University\Personal\RIDDUM\MDKPimPom\New 2017\iteration 03\JedShivaMeter code\jedshivameter-code-r16\x64\Release\JedShivaMeter.exp
1>LINK : fatal error LNK1561: entry point must be defined
1>Done building project "JedShivaMeter.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
Can anyone help me with this pleeeeeeeease?
