Step 1) Put together an email for a mock-client to exemplify how you would do so if working for ClickUp.
Step 2) Manually generate a message to a new mock-client for ClickUp to exemplify how you would do so if working for ClickUp.
Step 3) An interview with the supervisor of the department, followed by your demonstration of how to use almost all of the features ClickUp's product has to offer. I understand wanting to see how badly a candidate desires the position and even wanting to integrate a customer-mindset into the service role so they incorporate that understanding in their potential work, but requiring the interviewee to train themselves on how to operate the company-specific program at a level of being able to demonstrate it all within a short time limit before they are even hired is off-putting.