Flash no longer works - Mac

I keep gettting this error message. I am guessing that Flash has auto updated and now it does not work with the older software application that I am trying to run. It worked fine last week, but not now and I am stuck to know what to do. I have not updated my operating system on purpose because the software needs to be updated by the developer for it to run on the latest operating system. I am currently running Mojave. My software will not run on my work computer which is running Catalina.

It says: 

Director Player Error

This applicaiton requires an Xtra (Flash Movie...) that either does not exist or failed to initialize properly. Please make sue the appropriate Xtras are in the Xtras fiolder(s). 

Do I need to insall an older version of Flash to make it work again? and which one? 

Thanks for any advice.