Slack / Uber interview pointers please

Have onsite for Uber and first round with Slack next week for PM positions. I would be really grateful if somebody can share what these companies look for about when evaluating candidates. I’m also trying to figure out what slack cares more about as it’s Northstar metric: the number of active users or the revenue? And an active slack user might not be a happy slack user because they might be forced to use slack due to company policy so what metric do they use to measure true engagement? TC: 400 YOE: 20