Upload errors from pdf sheet music.

I have several pieces of sheet music on pdf, that I only need to transpose into a different key. The sheet music was purchased on a professional website, so the pdf has no flaws.

It uploaded great onto MuseScore. But when I open the file on my Mac, the music is full of errors. MuseScore gives me an error message tells me my file is being saved in MuseScore 3.2. How can that be? I'm using MuseScore 4.0. on my computer.

Can someone please tell me how to avoid all the errors on the sheet music I upload. Transposing only takes 3 seconds. But fixing all the errors from the upload is taking me hours. Please help?