Can't Open libEntititesMP.so

After compiling the source code for Serious Sam: The Second Encounter, I found myself getting this issue after running ./ssam:
"Cannot initialize classes:
Cannot load DLL file 'home/user/Serious-Engine/Bin/libEntitiesMP.so'"

I have all .gro files from my Steam install of Serious Sam: TSE in the folder Serious-Engine.