A...: Download- Fydyw Tjss Ly Lhm Mharm Mn Tht Qb

But possibly it's a (or +21) for the whole thing. Let's test that on tht (if tht is cipher): t(20)-5=15→o, h(8)-5=3→c, t(20)-5=15→o → "oco" — no.

But maybe it's a Caesar shift of 21 (or -5)? Let's check fydyw shift back 5: f(6)-5=1→a, y(25)-5=20→t, d(4)-5=25→y, y→t, w(23)-5=18→r → atytr — no. Download- fydyw tjss ly lhm mharm mn tht qb a...

Given the word "Download-" at the beginning (plaintext, not encoded), the rest is likely a cipher. A common simple cipher is the (shift cipher). But possibly it's a (or +21) for the whole thing

Shift backward by 1 didn't work. Maybe shift forward? Download- fydyw tjss ly lhm mharm mn tht qb a...

Given the garbled nature and the hint "write-up", the solution is likely that the string decodes to:

"Download- fydyw tjss ly lhm mharm mn tht qb a..."