Select the Resources tool from the Tool Menu of your site.
To grant uploading permission to group members, select Edit Folder Permissions from the Actions drop-down menu to the right of the group folder.
This displays the folder permissions.
Note: You will need to make the folder a group folder in order to limit uploading permissions to a single group.
In the student column, select Create resources, Edit own resources, Delete own resources, and Access/create group resources, then click Save.