Setp 1: Launch ExcelCalendar app and tap the Export button.
Step 2: Select calendars you want to export and then click the Next button.
Step 3: Choose the way to list events, set the start date & end date of export and then click the Next button.
step 4: Wait until the app generates the export file. After it finishes, select the "Dropbox" export option.
step 5: The app will open a page to ask you to authorize the app access your dropbox. You can tap "allow" to continue or tap "Cancel" to exit. Tap "Change" to change your dropbox account. (If you have already authorized before, the app will skip this step.)
Step 6: After tapping "Allow", it will return to the app again. Wait until the app display the fowllowing message.