Project Fitness Tracker to OD measurement device

Greetings I am new to the arduino / programmign environment and I was assigned a small project , I am following the attached instructions that uses the attached code in order to reprogram a fitness tracker into a device that measures optical density in liquids . Although i did what the instructions said many errors pop up , most of them are xxxxxx.h file not found and whe ni download the file to fix the issue another one pops up , or issues concerning the board not being compatible etc. .
Any insights would realy help , at the same time I will contact the source of the code for more information.

Instructions.pdf (1.41 MB)

BLESerial.cpp (3.6 KB)

BLESerial.h (1.53 KB)

odx.ino (9.56 KB)

SI114.cpp (10.3 KB)

SI114.h (11.2 KB)

Si114_defs.h (14.9 KB)