extension to read on Musescore portable

Hello all,
I usually use Muse Score on my personal computer, but sometimes use it on my professional computer, on which I only have MuseScore Portable (because my employer does not allow me to install the full software :) ). The problem is that, I can't continue a work started on my PC, cause Portable does not open Muse Score 3 scores.
I can't find any way to save MuseScore3 scores in another format, readable on MuseScore Portable: is there one ?

Thanks!
Flog