How many hours per week should you spend on this course?
Beats me. Too many variables. But I can give you a guideline to measure your progress.
There are about 60 exercises in the course. If you want to finish them all, you should complete about 6 per week, for a typical semester course.
Note the word "complete." That means your work is marked as complete by your grader. It might take you two or three attempts to complete an exercise.
Another thing. Exercises towards the end of the course are harder than early ones. They take more time. You might want to do the earlier ones at a faster pace.