The content:
Pulse-master/Software/Arduino/Protocentral_MAX30100.h
and
Pulse-master/Software/Arduino/Protocentral_MAX30100.cpp
files must be place inside of the
Pulse-master/Software/Arduino/example/PPG_plot
directory.
Reason: If you try to compile the PPG_plot.ino file with Arudino IDE, it will not compile, and hence you cannot upload it to the Arduino.