Before compiling and uploading the Bluetooth-System-Monitor.ino sketch, you will have to edit the User_Setup.h file included with the TFT_eSPI library to match the setup you have. This can be found in your Arduino skechtbook folder under "libraries". If you have not renamed the TFT_eSPI library folder, the file User_Setup.h can be found in TFT_eSPI-master.
You can use the files in this directory as an example for different boards and screens. Simple rename the file that matches your combination of board and screen to User_Setup.h and replace the file that is in the library folder. You can also copy the contents of a file and replace the contenst in the existing User_Setup.h
If there is a wiring diagram available, it is a .png image with the same name.
You can join my Discord server where I can help you out. https://discord.gg/RE3XevS