When clicking on an Open Activity from the Potentials page, I get an error -- Cases is not available in your edition.

When clicking on an Open Activity from the Potentials page, I get an error -- Cases is not available in your edition.

I'm not trying to create a support case. I'm only trying to create follow up tasks such as, Call John on Tuesday afternoon, and then mark those tasks as complete once they are completed. However, every time I click on an open task I am taken to a page saying that Cases are not available with my edition.

Please help! Thanks