Once I gave an interviewing candidate a simple assignment:

Create a (color) theme for a quarterly sales dashboard for CXOs.

‍I gave her 3 days for the assignment. The candidate reverted the following day with a JPEG file with not one but 4 color palettes. When asked about the reason for choosing the specific colors, she mentioned the colors were warm and calm. They also looked aesthetically pleasing when put together in a dashboard. But, she missed an important point.

The quarterly sales dashboard reflects essential data. It also needed to be legible on projector screens since CXOs would also look at the same dashboard with the broader team or board members in a board room (mentioned in the problem statement). Her color palette went utterly indistinguishable in the charts from one another when I plugged it into a medium-range projector screen.

As you are joining a team, spend a reasonable amount of time understanding foundational pillars -- in this case, genuine understanding of the user's environment: specifically, the target surface of consumption. It's real users you would be building these designs for -- not a 400x300 box.