If your computer is more than 5 years old, it might not have BLE (Bluetooth Low Energy), which is necessary.
If you do not have this function, do not worry! You can easily buy a USB dongle for a cheap price that will allow you to have BLE.
If you want to check if your Mac has BLE or not, type this in your console:
system_profiler -detailLevel full SPBluetoothDataType | grep "LMPVersion"
If you see a response like LMP Version: 0x6 Then you’re in luck,
If you see a lower value, like LMP Version: 0x4 Then you need to buy a BLE Dongle.