After you have opened a screen in the Screen editor, right-clicked a box on it and chose Properties in the pop-up menu, the Screen object properties window opens.
A box is for visually grouping screen elements. Screen elements that are placed inside a box become part of it but the frame is for cosmetic purposes only.

Click here for information on how to edit screen object properties in general.
On the current tab you'll find the following settings:

Field group

This option is not relevant to Axiell Collections and will be ignored.