We tested the code we found on Adafruit on our current "montage" and it didn't work.
This code was activating the vibrating motor when the tag reader detected a tag.

We decided to test an other code to see if the problem was coming from the vibrating motor : it was not. We were relieved to see that the motor was vibrating !

We found out that the problem was in the code itself : the connection mode needed to be in I2C.

But the code still did not work.

Then we tested the operation of the wiring that had been made on the tag reader with a multi-meter but everything was working perfectly.

Still, we decided to use an other tag reader and it wasn't working either.

Conclusion : we can't make this thing work (for now), we are going to struggle for 3 hours to fix it !