When adding a canvas to your design there are two options - you can add a canvas from your library options or you can add a blank canvas which will be demonstrated below.
How to add a blank canvas
1). Click the three dots (options menu) on the page you wish to add the canvas to and select add blank canvas.
2). The new canvas will be added to the bottom of the canvas stack on your page.
3). Click and hold the mouse button down, then drag the new canvas to the desired location on the page.