Preloading data in test server

I am trying to test a survey in the demo server, and was wondering how to preload test data. I can’t find anything on the interface that enables this. Is this possible on the demo server?

Apologies if this is a silly question. I have watched this tutorial on preloading Preloading - YouTube and don’t find it helpful - the batch upload button isn’t available on my interface.

It is in the context menu for the questionnaire, as shown in the video:

Dear Sergiy, thanks for this clue. However, I tried to do this, and these options created assignments, not preloading data. Do you know if exists another way to test this? Thanks!

Perhaps we have a different definition of “preloading”.
I am trying to use it in accordance with the Glossary .