I have been trying to add a texture to the editor but, whichever way I do it, through the + button at the top right or that larger + button at the bottom, the editor crashes immediately. This happens regardless of how many textures I have on the panel already. Is there anything I am doing wrong here?

Make sure you give editing permissions to all the folders. I had the same problem for a while. I eventually copied all of the folders outside of the data, gfx, and sfx folders into my documents folder so then I wouldn't have that problem.