DHL Versenden/Shipping for Magento 1
The module for Magento 1 can be found on the Magento Marketplace.
DHL Versenden/Shipping for Magento 2
The version on Github may temporarily be newer (higher) than on Magento Marketplace, because the release process on Marketplace takes more time.
The latest information about the compatibility with Magento 2.3 can be found in Github issue #44. You can add yourself as watcher to the repository.