This template is only available if Blizzard_Collections addon is loaded.
Either add this code to your addon, somewhere before you call
CreateFramePool.
Lua Code:
if not CollectionsJournal then
LoadAddOn("Blizzard_Collections")
end
Or make your addon load w/ Blizzard_Collections, you'll have to alter your addons loading process though, IIRC, you won't be able to use ADDON_LOADED event. For more info, search for "LoadWith"
here.