. . . . rescue your videotapes for mac. I can't anymore install the tool in my mac book air with os 11 . . . .
That is because Rescue your Video tapes for MAC is an old 32 bit program. MAC OS's starting with Catalina and now Big Sur no longer support 32 bit programs.
You do have one option to use the current software, and that is to use BootCamp to make your MAC dual boot and load Windows onto the second partition it creates on your hard drive.