When a Lesson Pack fails at the very end it's most likely missing the Lesson Pack Presets. To resolve this:

1. Go to https://www.mediafire.com/folder/w613i3996iati/Presets
2. Check the box on the left for each Pack of Presets that you need, and then click "Download" at the top of the screen (presets are not available for all packs).
3. These will download as one zip file. Once it's finished downloading, unzip it and place each Lesson Pack presets folder into
   1. Windows: C:\Program Files (x86)\VSTPlugins\Primer\Presets
   2. Mac: /Library/Application Support/Primer/Presets (note there's no "~" at the beginning. This is your main Library, not your User Library)
4. If that folder doesn't exist, create it, and place the presets there.
5. Windows Only: In addition, if you previously installed Primer and placed it somewhere else, also put a copy of these presets in its Presets folder as well.