Migration from ZCP 7.1 or earlier to Kopano Core 8.5 or later is no longer directly possible.
Starting with Kopano Core 8.5 it is no longer possible to directly to upgrade from ZCP 7.1 or earlier, as the database upgrade functionality for old Zarafa versions has been removed, see JIRA tickets KC-859 and KC-839.
Depending on version of your ZCP installation the database upgrade can take some time, take this in account when planning the migration.
Migrating from ZCP 6.40 or earlier.
Please contact support for more information.