Only the PACKAGE files containing scripts (in other words, script mods) are supposed to show in that list. If you do not see it in the list, unless the list is too big that part of the text is cut, then the mod is not loaded at all. In that case, I can't do anything to get it loaded.

If you're using NRaas ErrorTrap, you probably have some ScriptError files in your Documents\Electronic Arts\The Sims 3 folder. Can you check if they contain Adoptable Teens under "Loaded Assemblies"?

Is there also a way for a teenager to adopt another teenager?

With this mod, no.