If you want to save your design on IKEA.com, just click on the Save icon above the design.
You can also go to Summary and click on Save design in the upper right corner. Once the design is saved, the confirmation message will pop up and the button itself will fade away.
Saved designs can be accessed via main IKEA Kreativ page in the section My designs.
Make sure that none of the items you’ve added are selected (while an item is selected, you’ll see an item-specific menu, not the main one that contains the Save feature).
Tap the Save icon on the right side of the screen. The pop-up dialog will prompt you to enter a name for your design, then save it.