You can add the checkbox field to your document as either a single box or a group of multiple boxes.
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To create a checkbox group, add multiple checkboxes to the document and select the checkboxes you want to include in the group. Then, on the property menu on the right-hand side, click Group checkboxes.

Within the checkbox group, you can enforce a validation rule that specifies the required number of checkboxes the recipient must select. To apply the validation rule, make sure the checkboxes are selected and navigate to the Group validation property. From there, choose the desired validation rule to be applied.

If you want to remove the grouping of checkboxes, simply click on Ungroup checkboxes.