Hi gwcm ,
Thanks for your post.
There will be no problem unless you select the ‘Update’ option when importing ("kind of import" in the article you linked to in your post).
An ID is required because ATUM Export Pro allows entities to be linked to others using their original IDs. (e.g. you could import Suppliers, and then, POs related to the suppliers using the original IDs).
If you aren't going to import any related entities, just fill the field with consecutive values using spreadsheet software. They won't be used.
Best Regards,
José Andrés