Connect 24" Apple LED Display to M3 Macbook Pro

I'm helping a friend who is upgrading from a 2016 Macbook Pro to a M3 Macbook Pro.

Content has been transferred.

The friend wishes to retain the 24" Apple LED Display which has a Mini Display Port Connection (actually 3 leads out of the display).

So, I bought a Startech USB-C to MiniDisplay port adaptor but it doesn't work i.e., no picture shows on the external display.

I'd value advice on where I'm going wrong and what I can do to get the external display working with the new Macbook Pro.

Thanks