The backup contains the Boot Configuration Data volume which by default does not have a drive letter assigned.
Recovery Manager for Exchange expects all volumes to have a drive letter and as such it is unable to add the storage.
STATUS
This has been identified as a defect in Recovery Manager for Exchange 5.5.0 and was fixed in version 5.5.1. The defect ID is TF0271752.
Recommended solution is to upgrade to Recovery Manager for Exchange 5.5.1 or later.
For Recovery Manager for Exchange 5.5.0 there are two possible workarounds:
RESOLUTION 1
Extract EDB and transaction log files using Windows Server Backup to a separate folder and attach in RME as an offline Exchange Database.
RESOLUTION 2
Using Disk Management in Windows, assign a drive letter to the System Reserved volume. Backup the server and the new backups can be added in RME.
Note: a new folder name should be used for the new backups otherwise RME may still error and not add the storage.
