It depends on how you have configured security for that group.
Specifically, if you used an explicit deny for the group on that folder, that will override an explicit allow on the individual user. This is why we recommend using explicit deny sparingly.
However, if you used an implicit deny (that is, access is denied for group members because it was not granted, rather than because you checked "deny"), then you can explicitly grant the individual user the rights they need.
For more information, check out the conference course Overview of Laserfiche Security