The only 5‑letter English word that fits the pattern _ x _ x _ (same 2nd & 4th letters) makes sense after the word Download is “files” :

files → F I L E S Mapping from gives:

Next we test (L E V E L):

Download- fydyw nwdz bnwth msryh mn bnat altjm... The presence of is a strong hint that the rest of the line is a plain‑English message that has been encoded with a mono‑alphabetic substitution (each ciphertext letter always maps to the same plaintext letter).