Security/Privacy - How To Add App To "Screen Recording"

I use an online meeting application and need to enable "screen recording" in order to share my screen on online calls. However, the application is missing from the available list and there is no +/- option to add or remove applications (see screenshot).

How can I add additional applications to the "screen recording" list? I've seen a +/_ option in screenshots online and wondering how I can enable this on my computer. Thank you!

Using macOS Catalina Version 10.15.7. Can't upgrade to Ventura because my Mac is old.