Time.h working on Mac vs not working on Linux is explainable: A conflict with the C library’s time.h header paired with a case-insensitive filesystem, it can’t distinguish Time.h from time.h (see here.
That’s why all libraries that actually need to use the PaulStoffregen/Time should include it as #include <TimeLib.h>, and not #include <Time.h>. Then it becomes unque again with respect to #include <time.h>.