Showed Up to Work Sweaty Despite Using eBike - What Am I Doing Wrong?

I bought an eBike specifically so I could commute to work without showing up drenched in sweat. My commute is only 8 miles and mostly flat, so I thought this would be perfect. But I'm still arriving at work sweaty and gross, which defeats the whole purpose.

I have a Ride1Up 700 Series and I'm using PAS level 4 (out of 5) for most of the ride. I'm barely pedaling - the motor is doing like 90% of the work. But I'm still sweating, especially on warmer days.

Am I doing something wrong? Should I be using an even higher PAS level? Should I just use the throttle and not pedal at all? Or is this just what happens when you ride a bike, even an electric one?

For reference, I'm wearing normal work clothes (button-up shirt and khakis) and carrying a backpack with my laptop. My office doesn't have showers, so I really need to arrive not sweaty.

Do I need to change clothes at work? Buy different gear? Or is there some trick to riding an eBike without breaking a sweat that I'm missing?