The below is a challenge I'm trying to do. What I have done is, I have converted the value and the key to binary, separated them into 5 bits, added them up. When I got the answer, I then used the acii to convert it back to a word but the answer I get is vo, which looks to be wrong. Am I going about it the wrong way?

Decrypt the given xor ciphertext on alphabetic position.
Use ? for 0 and ABCDE to extend the set to 5 bits: key = cms.
Value jiBolgqdijct