How to make a cell a checkbox?

I see this response but I don’t know how to make the macros.
I’ve also tried the Form Controls but the checkbox is greyed out, so I can’t click it.

Any beginner tutorials for LibreOffice Calc that you would recommend as well?

I’ve also tried the Form Controls but the checkbox is greyed out

Generally this happens, if you are not in Design Mode, which can be enabled through

  • Second icon in first row of icons within the Form Controls toolbar

    image description

  • Tools -> Forms -> [x] Design Mode