Update: I used another method to build the socket.io library(cmake then build solution : GitHub - socketio/socket.io-client-cpp: C++11 implementation of Socket.IO client). I had to build boost(one of the Socket.IO dependencies) for 64-bit before building the actual Socket.IO C++ lib, again for 64-bit. I then used the same steps for linking it according to A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums and it seems to be working now.