Click on the Help button ❔ next to the Settings ⚙️ button > select ' ℹ️ About' (1).

A new dialog will pop up with the Calendar Pro 'Unique Identifier' (2)

Open Map Pro tab > click on the three dots [...] next to Trips > Connect (3) > Select Calendar Pro from the drop down arrow in the pop-up box > paste the unique identifier (4) > Save.