Try ROT13 (shift by 13): f(6)+13=19 → s, y(25)+13=38 mod26=12 → m, d(4)+13=17 → r, y→m, w(23)+13=36 mod26=10 → k → smrmk — no.
If we shift each letter backward by 1: f→e, y→x, d→c, y→x, w→v → exc xv (not a word). Download- fydyw tjss ly lhm mharm mn tht qb a...
Given the constraints, the most common trick for such puzzles: (each letter replaced by the key to its left on QWERTY). Try ROT13 (shift by 13): f(6)+13=19 → s,
Maybe it's a Vigenère? Key might be "download" or something. y(25)+13=38 mod26=12 → m