Not a silly question at all and i am glad you like the idea.

It is hard to put into practice what you learn without having excel. You can sign up for a free demo with microsoft and that will give you 30 days free. You can also use google sheets. Many things from excel work the same in google sheets, although for this post, it would be a little different.

Not all learn and earn activities need you carry out an activity with Excel, there are some in which your opinion or experience is asked.
Most of the activities on this post you can also complete without excel https://theexcelclub.com/excel-101-getting-started-with-excel-365/