Can't open my files on one drive as wel on my MacBook as online

Unfortunately I'm not able to add screenshots. Furthermore it is important tot know that I'm asking for my daughter Tatum Post that has a school account from the Universiy of Leiden: ******@umail.leidenuniv.nl. The school did provide with solutions but without result. They are not willing to ask Microsoft. This is the explanation from my daughter:

The onedrive app I worked with (the old version which is now not available anymore) indicates “De app is niet gevonden” Which means “The app is not found”. Since that update in the menu on the left (in finder) two versions of onedrive are mentioned. When I try to open a file stored in the old version where all of mij files are stored, I get a notification. This notification states: Er is een fout opgetreden bij het openen van het bestand in Word.

U kunt het volgende proberen.

•⁠ ⁠Controleer de bestandsmachtigingen voor het document of station

•⁠ ⁠Controleer of er voldoende geheugen en schijfruimte beschikbaar is

•⁠ ⁠Open het bestand met de conversiefunctie voor tekstherstel.

(bestandsnaam).

In the second version of onedrive, the new, version, of the app onedrive on my macbook there are only a few files left. Now all the files I saved on onedrive since half of september are gone in this new verson of onedrive which means I cannot open them anymore. The other files I saved before half september are transposed well to this new version of onedrive, these files do open. Via the ICT department of the University of Leiden many possible solutions were tried already. Hopefully you can help!

Sorry to hear that you are experiencing this issue. Could you please share more information about what happens when you try to open these files? Do you see any error message? If so, please share a screenshot to better understand the situation.

Also, is this happening only with those specific files, or does it happen with other files as well?