I would estimate the course will take about 4-7 hours.
Each of the three modules takes about 30 minutes to complete (1.5 hours).
In addition to the three modules, there are worksheets for each section. This may take 20-45 minutes per worksheet (1-2.25 hours).
Once you receive each worksheet back, it may take an additional 10-30 minutes to review the feedback and make the necessary changes (0.5-1.5 hours).
This leaves 1 to 1.75 hours for any speed bumps along the way.