Both are correct ways of saying it, just depends on the level of formality you want to use. तू is generally a disrespectful word, I would advise against using it. Sadly much of this course uses it as an example instead of आप
Aapse is used for an elder. Tujhse for a younger. Tumse is used for any your age. Here we can use any of the three. I am a native hindi speaker here to teach my youngers .