How do I show Follow-ups in my calendar?

Calendar Sync is free on iPhone, iPad, and Android. This answer covers iPhone and iPad, and How does Calendar Sync work on Android? covers Android. During first-time setup, or from the invitation in the notifications tray after updating, tap Add to Calendar to create a WitnessWork calendar (in iCloud when available). You can also set it up anytime in Settings → Preferences → Calendar Sync: allow full calendar access, then create a WitnessWork calendar or choose a calendar used only for WitnessWork. Updates need iCloud sign-in and an internet connection, even for Google or Outlook calendars. To use Google or Outlook, create a calendar with that provider, add the account in iPhone Settings → Apps → Calendar → Calendar Accounts, and turn on its calendars. Your default calendar and calendars stored only on this device can't be selected. Once a calendar is selected, every upcoming Follow-up is added automatically, including ones you already saved, as a 30-minute event. Calendar Sync adds all of your upcoming Follow-ups or none; to stop adding them, turn it off in Settings → Preferences → Calendar Sync. Past Follow-ups, service Plans, and recurring Plans aren't added. Each event gets the same alert as its Follow-up's Notify Me reminder, and no alert when Notify Me is off. Your calendar provider may add its own default alerts; for Google, remove them under that calendar's Event notifications in Google Calendar settings. Make changes in WitnessWork, because calendar edits, including alerts, may be replaced on the next update.