oh figured it out, nvm

@Gestour but mine doesn't do that, it doesn't show sp on the app that you can open it with.... im so frustrated for like two days and still I can't figure out how to put the DAMN MODS ON THE GAMEEEE!!!!! MANNNN

@Gestour hello do you know if theres a way to directly downlad the xml file because i have to port them to a diferent divice that cant downlaod stuff

Open the game, and go to download planes.. They should download right into the designer. Then save.
If you download planes from the website on another browser, you just end up with the splane file. But, I think you can right click and select open with simpleplanes, and it will open SP then download the plane (on pc)
Not sure if that makes sense.

@Gestour How?

I think splane files are just links to the xml file on the website. It's the XML you want.