Target Display Mode isn't working.

Hello, I have an issue to do with my mid 2011 iMac and Target Display Mode.

I was given a 27-inch, mid 2011 iMac with macOS High Sierra Version 10.13.6 by my college. My plan was to use it as an extended monitor for my 13-inch, Early 2015 MacBook Pro with macOS Monterey Version 12.7.6. I did some research and found out what Target Display Mode is.

When I was given the iMac the apple keyboard and mouse was not included and I do not own any.

I purchased a THUNDERBOLT Video Cable and plugged it into both the iMac and the MacBook.

I was told that the windows key translates to the Command key on my keyboard however upon pressing Windows-F2 (cmd-F2) an alert beep sounded.

I was then told to go to System Preferences>Keyboard and check "Use F1, F2, etc. keys as standard function keys" but the iMac doesn't have that option.

I would be extremely thankful if someone gave me some advice or solutions to my problem.

Thank You