How can the "Deltalog" be "installed"?
Migrating magento 220.127.116.11 >> 2.1.0
Migration Tool Version 2.1.0
In order to run
bin/magento migrate:delta step you first need to run the
bin/magento migrate:data step because it is in this step where the Data Migration Tool creates triggers in the source database.
Those triggers will be used to pull only the changes made in Magento 1 since the last time you migrated data.
For more information have a look to the Official Documentation.
Hope it helps.