Target Display mode 21.5 inch iMac (Mid-2011) via MacBook Air 2020.

I recently purchased a MacBook Air and would like to use my old iMac (Mid-2011) as a display. However, i am unable to place the iMac in Target Display mode. I am using a Thunderbolt to USB-C cable. Unfortunately I do not have the original keyboard for the iMac, and I am using a third party keyboard... I did download virutalkvm to try to bypass the issue with the keyboard but still cannot get the iMac to go into TDM. Is there anyway to put the iMac in TDM without the original keyboard. Do I have a cable issue since it is a Thunderbolt to USB-C?

Any help is appreciated.