If you do not specify both the Web Part Storage Site and the Web Part Storage Library, your new roll-ups will be saved to the default web part gallery on your server.
You need to be logged in to the site with Site Collection Administrator rights. Only site collection administrators can save web parts in the web part gallery.
The Roll-Up Wizard does not load web parts directly from the web part gallery. Instead, to load a web part into the Roll-Up Wizard, you must have the web part instantiated on a page.
CorasWorks roll-ups do not support more than 20 columns of data, including search columns. As more columns are added to a roll-up, the search process will become noticeably slower. CorasWorks has also found that in roll-ups with more than 20 columns, the data is not always returned as expected. We recommend that for optimum visibility, usability, and consistency, you try to limit the number of columns to 6 or 7.