Hi Jerome,
Based on the error message it’s indicate that the import service for your region has not been rolled out yet.
However, Network upload is currently available in the United States, Canada, Brazil, the United Kingdom, Europe, India, East Asia, Southeast Asia, Japan, Republic of Korea, and Australia. Network upload will be available in more regions soon.
For your reference see under FAQs: FAQs for using network upload to import PST files
Your time and understanding will be highly appreciated.
Best regards,
Shyamal