I don't know what you have promise in the interview but it seems like your ability doesn't compatible with what the position requested. As I may know interior design is more towards compatibleness of the internal house outlook. There are mostly managing skill require. To perform the task you need to collaborate with the customer contact and keep updating their ideal interior design. It is super crucial the final outlook will be acceptable as for the customer. If what is promise doesn't convey in the real enforcement it means you fail as a interior designer.