Can't install/update nuget packages

I run into an issue when trying to compile an open-source github project ;

I launch Visual Studio Community, then try to update the nuget packages but to no avail ; I get the error

"An error occured while trying to restore packages: Unable to findversion '1.0.0' of package 'vcpkg.C.dev.vcpkg'."

I tried looking on the internet, installed vcpkg and did everything right, but still, it stays here. I tried to check if I can do anything by restoring nuget packages, but still, nothing is working