Calcurates allows you to connect your Royal Mail or other carrier accounts. Connecting a carrier account with Calcurates requires account credentials and IDs, depending on each carrier. In your Calcurates account please proceed to Menu
and in the carriers grid click "Connect Carrier"
in the Actions column for the needed carrier.
For more detailed info please read this guide
which will give you more instructions on how to connect your account to Calcurates.