It seems that the library libFlurry.a isn't properly added to your project. It should appear in the second screenshot.
Click on the + icon at the bottom of the Link Binary with Libraries view (second screenshot) and select the libFlurry.a file. Then build again.
Actually, you also need add the following frameworks:
CFNetwork.frameworkSecurity.frameworkSystemConfiguration.framework
I don't know why but my libFlurry.a file is located IN the pod folder named as "libFlurry_6.7.0.a". I am not sure whether I am being stupid here, but just in case someone like me don't know where to look for it...
After adding it, it works.