After reading online my iMac should work as a second screen for my new macbook. I have a thunderbolt to usb-c adapter and have been pressing command+f2. Below are the specs of my iMac, my understanding was that it wouldn’t work for late 2014 onwards, so why isn’t this working for me please?

iMac (21.5 inch Mid 2014).

1.4 GHz Dual core Intel Core i5.

8GB 1600 MHz DDR3.

Intel HD graphics 5000 1536 MB.

Thanks.

After reading online my iMac should work as a second screen for my new macbook. I have a thunderbolt to usb-c adapter and have been pressing command+f2. Below are the specs of my iMac, my understanding was that it wouldn’t work for late 2014 onwards, so why isn’t this working for me please?

iMac (21.5 inch Mid 2014).

1.4 GHz Dual core Intel Core i5.

8GB 1600 MHz DDR3.

Intel HD graphics 5000 1536 MB.

Thanks.

EDIT

I'm using a Macbook Air 2020 version that is running Catalina 10.15.7. The iMac is running exactly the same OS.

The cables I have are Thunderbolt into Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter.

When I press Command + F2 absolutely nothing happens, no sound, no change on screen at all.