When you first create an account, Appointlet will present you with the option to connect an email calendar account. If you do so, the following screen appears to ask whether you'd like to add meetings and check for conflicts on any specific calendars:
Once you've selected the email calendar provider, you'll be prompted to log into your calendar account to establish a connection. After connecting, you'll be presented with a menu where you can choose which calendar to add meetings to, as well as which calendars will be checked for external conflicts to prevent from double booking over existing commitments.
Keep in mind that meetings can be added to only one calendar at a time, but you can check as many external calendars for conflicts as you'd like.
If you already completed the setup wizard and still need to assign a Meeting Calendar for your scheduled events, start by clicking your username in the upper right corner of the dashboard. Then select Calendars as shown here:
From the calendar menu, you can edit the same calendar collections mentioned above by clicking the Change button next to either area.
This will open a new modal where you can select additional calendars from the dropdown menu.
With meetings assigned to a calendar, each meeting scheduled through Appointlet will generate an event in your calendar. Here's an example of what one of these events look like in Google Calendar: