Depends on the addon.
- If it's under the GPL, MIT/BSD license, etc. or if it includes any kind of note that clearly says it's okay to include in compilations, then you don't need permission.
- If it doesn't include anything that says whether it's okay, then technically it's not okay, and you should get permission, though most likely the author doesn't mind.
- If it clearly says it's not okay, or includes an actual copyright notice or a statement like "All Rights Reserved" that makes it obvious the author is aware of that stuff, you should get permission.
In practice most compilation uploaders don't ask and don't read anything, so the fact that you're even asking if you should ask puts you ahead of most.
Other good practices that will make addon authors look more favorably on you:
Include a link back to the addon's download page on your download page, so if the user has problems with a particular addon they know where to go for help, and they can update the addons themselves without you needing to re-upload the entire compilation all the time.
Don't modify the addons. Users don't read (yes, it's a generalization, but it's also very often true
) so even if you mentioned on your download page that a particular addon is modified, if they have a problem with it, they're probably going to go ask the original author for help, and the author will waste their time trying to figure out how on earth that can be happening with their code, only to eventually find out the problem isn't in their code at all. Modifying the addon also means users can't update it themselves, and are likely to accidentally overwrite it if they use Minion or the Curse Client. You can almost always make any changes you want from code running in a separate addon, so if you want to make changes, create an addon called PolitigUI or something, and put all your modifications in there.