A handy chrome extension for downloading all the documents in the group.To see it in action go to files tab of that group and click the extension.

Since its still in beta , not published to the store.To use :

1.download the folder , and get the .crx file from it.

2.go to chrome:https://extensions in your browser

3.Drag the .crx file to that tab and install it(may have to enable developer mode[a small checkbox on the upper right corner of that tab])