I've been also stumbling over the missing Cairo libs and having to build yourself when starting with IPlug - Youlean and it took me a bit to figure it out (find an older relevant post in this thread).
Would be helpful I think if the first post could be updated with this info (currently it says 'All libs for MSVC2015 and 10.7+ XCode are included').
edit:
Maybe also that use of Cairo can be disabled by not defining (commenting out) '#define USING_YCAIRO' in IPlugBase.h, which also took me a bit to find out (but maybe it's just me
).