*Edit: I got CURL working in VS 2017 on a 64 bit machine following these steps (see below for original problem):
First install vcpkg:
You've installed the x86 version of curl with vcpkg (That's the x86 in vcpkg\packages\curl_x86\include). You need to install the x64 version to match your project:
vcpkg\packages\curl_x86\include
>vcpkg install curl:x64-windows