Coolsville

You have to get Coolsville (to get Milo) if you want to use the outfit.
Should be in the store:

NEW : GameOfGamesTheSequel_CoolsvilleComics_IN - 2020-06-10 15:00
NEW : GameOfGamesTheSequel_CoolsvilleComics_OUT - 2020-07-16 15:00

Coolsville and Milo are in the Game of Games The Sequel store section for 150 donuts and they're also in the yearbook mystery box for 30 donuts (or 150 donuts in the yearbook plus 4 other items max).

"mandiepaxton;d-259613" wrote:
I’ve just unlocked the outfit on the game and I go to use it and it says - you must build Coolsville to unlock Milo. Is there anything I can do, or is this part of the story going forward?

Mands xxx

As everyone has mentioned you need the character in order to use the skin (or outfit if that's less creepy).

This will occur anytime you obtain an outfit and don't have access to the character, it will be stored in your inventory until you unlock the necessary character.

As people mentioned it should be available in the store for donuts.

Thanks everyone. I went in and looked, don’t think it’s worth the 150 doughnuts so won’t bother.

Mands xxx

Grab it from the yearbook you even if you miss it in the first go u still end up with stuff

"mandiepaxton;c-2138671" wrote:
Thanks everyone. I went in and looked, don’t think it’s worth the 150 doughnuts so won’t bother.

Mands xxx

I saw it in the store and decided "Nah" as well, and there's other stuff I want from the Yearbook first, so Milo's going to be a while.

I got it in all 3 of my games. I think I spent 30 minutes Refreshing over and over to get a good combo in my Fire game though (my Galaxy and iPad games had good enough combos, so I just let them be).