Issue: Issue is due to the lookup records (Company Name) not found in CRM database.
Solution:
First you need to import the customer. Once the import completed, you need to import the contacts with allow duplicates.
Note: Please check all column properly in both file.
Sample files:
https://gcubeftp.gc-solutions.net/IT/Home/Manuals/Sample/Import_Contacts.xlsx
https://gcubeftp.gc-solutions.net/IT/Home/Manuals/Sample/Import_Customers.xlsx