Try reading it and see! There’s probably not a really satisfying answer for the general case. It’s one of the great works of literature as well as philosophy, a cultural monument and apex and touchstone in its own right; and it is as open to you as it is for anyone for an immediate encounter. I would really suggest that in general don’t be worried about not being ready for a work, especially one as important and broadly relevant as The Myth of Sisyphus. Human culture belongs to everyone, and you don’t need to understand every reference to get most of the value out of a work.
You can make a note to look something up later of course, but especially on a first pass and first encounter with a work that might be or seem challenging, maybe just focus on the broad structure of the work, trying to understand as much as possible very quickly. (Maybe try to actively evaluate what “level” the material is — are you completely lost, or is it just a little elusive; or is it “just challenging enough” etc.)
Reading comes in revisions and drafts, too: gradual approaches that recursively construct a model of the text. Alternatively go slow and allow yourself to process and understand every beat. Really these two strategies are fused: you are moving just quick enough to keep momentum going and also just slow enough to permit things to cohere. Possibly reread where necessary, take notes or draw pictures, and ask yourself questions about what you’re reading. Reading strategies are ultimately going to be singular yet share this recursive-progressive structure of gradually elaborating the semantic content through a dynamic between thinking and “moving” . Perhaps the text is a rock you have to push up a hill endlessly, and each time the groove is worn in a little deeper.
(We could produce a bunch of meta-level commentary about the work but I’m not sure how enlightening that might really be. That said and very broadly speaking, and compared especially to other existentialists, perhaps we can say the Myth is not particularly challenging at a conceptual level necessarily — but rather at an emotional and intellectual level, and maybe a spiritual or aesthetic one. It is aimed at a more general readership than lots of philosophy; it does not seem to require a lot of technical preliminaries: and so on.)