Since an ADB database has some restrictions on the object types and Oracle Database Options you need to use a logical migration method rather than a physical one.
The main migration tool for migrating to ADB is Data Pump. You can export your schemas and import them into ADB using Data Pump. To sync up the additional/incremental changes on the source database during the export/import process you can use GoldenGate or GoldenGate Cloud Service to replicate those changes to ADB.
In the current release you cannot use physical migration methods like backup/restore, Data Guard, Pluggable/Unplug , database clones, and transportable tablespaces to move your existing database to ADB.