"Dad drinks the soup slowly."
Translation:אבא שותה את המרק לאט לאט.
Basically yes, do note though that לאט לאט means reallly slowly so it's not incorrect, but it increases the image of the slow rhythm
The given solution by Duo is "לאט לאט", I didn't make it up :)
I noted about the removal of "את", because it's possible.
About this particular answer, if you ask me I agree that "לאט לאט" isn't the exact translation here, and a better translation will be "באיטיות"