Hello,
Below is the list of few apps on which you can do course on Digital Marketing:
Coursera, Udemy, edx, Udacity, Futur Learn, Skillshare, BitClass, Upgrad, Simplilearn
Other than these, there are plenty of other YouTube Channels where you can learn about digital marketing,
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile