adobe flash for MAC OS Big Sur 11.1

You won't be able to use that software any longer. Contact Cengage and ask them why they have not made the technology transition that everyone has known was coming for at least 3 or more years.

You don't. Flash has reached end-of-life. Why do you need it?

Flash is dead. Support for it ended entirely on 31 December 2020. All flash content everywhere will cease to function tomorrow.