When importing your data into the repository, you have to make sure the file is comma separated (.csv), tab separated (.txt or .tsv) or Excel (.xlsx) file. Also, you have to match the columns of your uploaded file with already existing columns in database.
If your file includes columns that are not in the repository table (e.g. References) you need to create the column in the repository first and then match the columns accordingly.
For easier understanding, please see the GIF below.