I have to import users from a drupal 6 site to a drupal 7 one. I'd use https://www.drupal.org/project/migrate_d2d but i have several limitations on what i can do on the databases: 

- I can't access the drupal 6 DB from the drupal 7 installation 

- I don't have ssh access on the D7 server, i can interact with the database only from phpmyadmin

- I can't create new databases on the D7 DB (i can create new tables though), and i can import sql files only to a maximum of 10MB. I can't upload a file on the server then import it from local either

In addition, user roles are different from the 2 sites so i need to map them before importing.
I think the best solution is to export data from the D6 site in some format and the import it on the D7 site but i don't know how to do it