I believe you are correct. If you see the "Go PRO" symbol in the upper right hand corner I think it mentions one of their paid "perks" is not having to publish all of your ideas. That looks to be $9.95 a month though.
When you are making your chart there should be a Camera Icon at the bottom right portion of your screen. I am new to this also but you click on the camera and then it gives the option of saving a link or "Save Image". You click the save image and it creates a .png file that you can copy and paste somewhere like Word or wherever else.