The key and driver are required to access the data. Neither is stored on the external HDD. The only method to access the data on this drive without it connected to the system would be to utilize the DETech disk and authenticate using the Recovery XML.
From where can i download Key and Drivers,
It is not possible for you to utilize an MDE encrypted HDD as typical removable media. The driver is a part of the software install and the key is stored in a custom file system. If the data needs to be accessed for recovery purposes, the DETech disk can be utilized which has the driver and the key can be exported from ePO.
If you require an encrypted removable drive, File and Removable Media Protection (FRP) would be a better solution which allows for authentication to the drive from any system.