Inviting/Importing users and confusion

Hi,

When we invite a new user (who has no omeka account previously) from our omeka.net installation, the following page is shown to them:

https://www.omeka.net/signup

We have found that a lot of users get confused that they have to pay to access the site and completely ignore the basic plan option. Is there a way to bulk import/invite users so that they are all given basic accounts by default?

Thanks,
Masud