If you have the subscription version ("365"), all you need to do is open the Cyberlink Application Manager and scroll through the list on the
Packs menu tab, then click on
Download for any packs you want to install:
If you have the stand-alone (lifetime/perpetual license) version, you would have been provided with a zip file with all available packs when you purchased PD17, but it's been a few years since I've had a stand-alone version and I'm not sure how Cyberlink distributes new packs these days.
If you look at the table (a little past halfway down) on this comparison
page, they make clear that subscribers have access to all packs when they first come out, while non-subscribers are limited to 6 packs, 50 tracks and 100 clips.
Hopefully another member will post about how to get access to the Music Festival Pack for non-subscription users.