Many thanks for the pointer, I didn't notice it was a Linux library.
Once this was sorted, and after a few more attempts (Linux issues), I managed to run the demo program, which worked. I am now in a good starting place to figure something out with the logger. Thanks again for your help.
In case it's helpful and relevant, I've noticed 2 bugs (which might be Linux ones):
#1. Running ./autogen throws an error from aclocal which cannot find the m4 directory. Creating an empty m4 directory solves the problem; maybe this could be added to autogen ?
#2. Running ./configure throws an error about an unexpected fi at line 18833. In the configure file I have (from the Pico installation file), there's indeed an empty else statement line 18833. Simply adding a : after the else resolved the problem. Maybe this could be fixed too?