STMicroelectronics ST-LINK/V2-1 USB driver for macos?
The cradle expansion board cannot be used to program the SensorTile module. The USB port on this board connects directly to the module -- it's there so that you can program the module to behave as a USB device, and connect it to a computer.

You will need a separate SWD programmer to program and debug this part. Many of ST's evaluation boards, including most Discovery and Nucleo boards, have an integrated ST-Link programmer which will work perfectly. Remove the ST-Link jumpers on the other board, then connect the SWD pins between the two boards with jumper wires. (If you aren't sure of the pinout, check the schematics!)

DO NOT plug the Cradle Expansion Board directly into a Nucleo board using the Arduino shield connector. This won't work, and it might damage one or both boards.