See that message above?
The Font in your design has gone missing. In order to make your stickers, we're going to need to get it back.
A lengthy hunt of the Font file isn't completely out of the question, but if you really want tackle the issue at it's source just convert your Font to outlines.
Here's how to in Adobe Illustrator:
1. Select all live type.
2. Click Type Menu > Create Outlines
3. Save your file.
This turns the letterforms into shapes, preserving the type on any platfrom and also avoiding a common misstep in the process of ordering your stickers.