External devices

I made a back-up CD (of a novel I'm writing) before my old iMac crashed. When I brought home my new IMac from the Apple store ,where the service reps were all illiterate, SURPRISE! No slot for CD/DVD! ˆnow have come to realize this is now common to all newer computers. On Amazon there are numerous devices called "readers", but all the reviews state they are not compatible with Catalina 10.15.5 which my new computer has been upgraded. "Chat" with Apple store, still illiterate. Can anyone advise me about an external reader to put my novel back into my new computer? "Grandma" is a dinosaur when it comes to computer talk, so please use small non-tach words.