The project lacks quick-start examples for inexperienced developers. There are great examples in samples folder, but they are hard to start by. First, they are big, when users want to see the minimal working example. Second, the build script (cmake based) is interlined with the main lib build. You have to dissect the CMakefiles.txt and extract related parts to combine them in separate build instructions.

I have experienced these problems myself and wrote libupnp_example project (https://github.com/Zapunidi/libupnp_example) to save others from this fate. It is a simple SSDP client based on libupnp, that I tested on Linux and Windows (Mac OS will be next). I didn't offered this as a pull-request because its simplicity and separateness doesn't go in line with pupnp approach, to integrate it by myself.

I suggest that you use my project in any way to help your users, to lower the entry threshold: integrate, put a link in readme, etc. I may do some work to improve the example according to your advice's.