Dear Romane,
If you have used the template provided by REDCap (under "Data Import Tool") there should not be any issue.
Note that, as specified in the REDCap "Data Import Tool" interface: The data file will be checked for errors to ensure that all the data is in the correct format before it is fully imported into the project.
Be sure then to leave this option as default:
Nevertheless, if you are still worried about importing the data, send us an email at redcap@unifr.ch and we will setup a Teams meeting to guide you through the import process.
Best,
C.