As the import may take some time, the script should be called from the command line of your server.
which means that it is depending from the script runtime (max_execution_time) and the size of data you have to import. So maybe it would work without any hassle from your browser as well otherwise ask your provider to increase the execution time for a moment. Just give it a try.
Thanks for the fast reply - very much appreciated!
Unfortunately it does not work since the script is not passing any mySQL user and password entries and therefore the script termiates and claims it cannot access the osCommerce database
Do a parallel installation of an OXID eShop on the server where your osc runs. Probably the database of your osc doesn’t grant any access from outside the server. Maybe this is the point. Afterwards, you might easily move the OXID.