That would be a better question for IKEA's support team.
http://www.ikea.com/gb/en/customer-service/
However, if you are running High Sierra, then it appears the IKEA Kitchen planner is not supported on your computer:
Mac Browsers:
Mac OS X 10.7.5 Lion and Mac OS X 10.8.2 Mountain Lion
Safari 6.0.5 Safari 7.0
Firefox 23
Chrome 29
Mac OS X 10.9.0 Mavericks
Safari 7.0
Firefox 23
Chrome 29
Note! IKEA Home Planner only support 32 bit browsers (not 64 bit).
The Safari Browser on High Sierra is by default 64bit. Also High Sierra is not listed as a supported OS X version.
http://www.ikea.com/ms/en_MY/customer_service/ikea_services/kitchen_planner.html