Can I use my coupon and account credits on the same order?

Yes!

For iOS: To apply a coupon code, tap on Promo Code on the Checkout screen and enter the code you received. Any available credits in your account will be automatically applied to your purchase and listed in the Order Summary at the bottom of the page.

For Android: To apply a coupon code, tap Have a promo code? link on the Checkout screen and enter the code you received. Any available credits in your account will be automatically applied to your purchase and listed in the Order Summary at the bottom of the page.