While testing, I've found that this app works perfectly on Chrome, Firefox, and Edge. But, it didn't work on UC Browser.
Remember that this app works perfectly on the private mode of the browsers (Chrome, Firefox, and Edge) too.
Also, keep in mind that you can edit the plan at any time you want.
To modify the plan, first, you need to stop the plan (if it is active) and then tap on it. Now, you can see "Edit" option at the bottom. Tap on it to edit the plan.