How do i get add-ons to work?

[Darkspyre Guardian]

add-ons are downloaded, but can't be used in-game. how do I fix this?

[Ad Bot]

[KoopaScooper]

Look through the window that pops up when you click "Start A Game".
If there's a button called "Add-Ons". Click it.
Make sure there's a Checkmark in the box of the recent Add-Ons you've installed.

[Meekl]

Dun't be a Saber Ninja