Hi libriomancer,
The Donator pack is visible under the Season #1 Packs icon, and can be started as a standalone package.
As for the Season #2 Challenge #1, #2 and #3 packs, they usually add items which are usable by all other characters in the same base and theme, so you should find them by opening the Settings menu after selecting a character in the main menu and proceeding to the Editor. On the Settings screen you can click the icons to make those packs active and see their content in the Editor.
Please let me know if you still don’t find them for some reason.