So I bought Tm2 stadium 3 days ago and before that I had Nations Forever.
When I download a map it opens it in Nations Forever and I can't fix it. I even deleted Nations Forever but still opens it.
When I press Install & play it does nothing and I have popups enabled.

Thanks

Install & Play uses the maniaplanet:// protocol in your browser. Usually the first time you click a link it asks if you want to launch maniaplanet with it. But if you ignored it, then it can be problematic to set up later. Install & Play actually downloads the map from within the game by launching a manialink.

But regarding map files themselves....

TM2 and TMNF use the same .gbx file extension for maps, which is probably causing the issue for downloaded maps. When you installed ManiaPlanet it should have asked you if you wanted to associate gbx files with it. If you said no, then that's probably why it's not launching ManiaPlanet when you open Gbx files.

Assuming you are playing the non-Steam version...

You can always download the minimal installer again from http://files.v04.maniaplanet.com/setups/Maniaplanet_Setup.exe

It's only a 70MB download.

And just install over your current copy. It should ask you again if you want to associate Gbx files with it.

Thanks ! It's working now