Can’t transpose

There no non-free version of MuseScore, not here on musescore.org. and none than can't transpose

Download the free (at no cost to you, or anyone else) full-featured MuseScore Studio score-writing software from here:
https://musescore.org/en/download
Install it on your computer, and you can create/upload/download scores, play them on your computer, and edit/transpose at will.

You should look at this:
https://help.musescore.com/en/articles/8535860-what-is-the-difference-b…
and:
https://musescore.org/en/node/277874

You likely signed up for a free trial subscription to the score-sharing site at musescore.com.
Presently, you are at a musescore.org forum.