Thank you all! I finally did the uninstall for MFS2020 in-store version and installed the Steam version.
When I first luanched the Steam version, MFS2020 did ask me to login into the microsoft account, however, the worst thing happened, none of my settings (graphic, joystick profile, aircraft view) were saved, I spent nearly 3 hours setting everything right, which is sucks.
My original plan was to delete the MFS2020 store version's client and kept the Sim folder (community), so I was hoping that I could save another 3 hours of download when I launch the Steam version, too bad this did not happen, the steam version did not recognize the original sim folder, I tried to change the sim folder location in the userConfig file, but still did not work. So I had to download the entire sim again.
One good news though: since I kept the original sim folder, I just moved some of the sceneries I bought (not from MS store) to the new sim folder, and they worked!
So for anyone who is thinking about switching from the store version to the Steam version, I highly suggest taking some pictures of the joystick settings and graphic settings, just in case.