Exporter for Contacts 1 is now legacy software. If you use macOS 11 Big Sur or newer, use Exporter for Contacts 2.
Apparently, you accidentally have denied Exporter for Contacts to access your contacts. Click here for instructions to fix this.
Use Importer for Contacts to import stuff into Apple Contacts. Importer for Contacts was developed to overcome all the limitations of the import function available in Apple Contacts. It can read Excel files, supports custom labels, automatic group assignment, and more.
It's simple: Create a Smart Group in Apple Contacts that contains only contacts with the desired criteria. Then drag the members of the Smart Group to the contact list of Exporter for Contacts.
Of all things, Excel fails to recognize a CSV structure - Apple Numbers is much smarter. The trick in Excel is not to simply open the file, but to import it via the menu command File > Import. Then follow the instructions. Exporter for Contacts also supports the native Excel format. So just use that and you won't have to deal with such problems.
This is quite normal if you have many contacts, use many different labels and have set the export of multi-value fields so that they are packed per label in a separate column. Just exclude unimportant fields from the export and let the multi-value fields export in list form by using the special "Labeled List"/"Unlabeled List" labels.
Exporter for Contacts is designed to work directly with Apple Contacts and uses its database through a special interface provided by Apple. This is the best way to ensure data integrity and privacy when handling your contacts. You need to import external vCard files into Apple Contacts first, so that Exporter for Contacts can access these contacts.
A Contacts Archive (.abbu) is a proprietary format that Apple Contacts can create to backup all your contacts and Contacts accounts. It is not intended and made to be read by third party apps.