Hi @jackfr0st11, welcome to the forum.
I won’t encourage you to use JuMPER; as others have said, it isn’t maintained, and supports only old versions of JuMP and Julia. This will make it impossible to use with newer versions of solvers like Gurobi, and you’ll need to refer to old versions of the JuMP documentation.
But for this specific error, I think you’ll need Clp v0.7 or earlier. Try ] add JuMPER JuMP@0.18 Clp@0.7