As Musicman Dan indicated it's just getting the PAK installed and StylePicker updated.
Here is a screen shot of the StylePicker window with the filter set for XtraStyles PAK # 7.
Open the StylePicker window after installing XtraStyles PAK # 7 and you will see a green text on black background notification at the left, top of the StylePicker window. The notification suggests performing a fast rebuild.
Click on the Rebuild button at the bottom of the StylePicker. Select the fast rebuild option if you do not have third party (Norton) styles or slow rebuild option if you do have third party styles.
Once the rebuild has completed, select the "Other" filter stream and you can select to show none, all or just XtraStyles # 7.
Description: StylePicker open with "Other" filter window open and XtraStyles # 7 selected.