Textures broken after importing to Unity

I made some trees in TreeIt tree generator and imported it to Unity. It was fine until I converted dds files to jpg files and it started doing this:

I know it has something to do with transpanency, but I don´t know how to fix it. I also have exported some other textures from editor, that I don´t understand how to use (like the ones with purple colors).

JPG can't support transparency because it uses RGB color space. You should use a format that allows transparency, like PNG.