The USB port on the My Cloud is designed for attaching external USB hard drives to the My Cloud. You cannot use it to connect to a PC/computer to transfer data to/from the My Cloud to the PC. The My Cloud is a network attached storage device (NAS) not an external USB hard drive.
Officially the single bay My Cloud units do not support syncing/backing up to Google Drive or other cloud storage services. Unofficially it may be possible if the Google Drive sync software (Download - Google Drive) on the local PC and configure the software to use a “mapped” My Cloud Share on the local PC.
http://support.wdc.com/knowledgebase/answer.aspx?ID=2676
Another possible unofficial option is to use Goodsync to sync/backup My Cloud data to a cloud storage service or to another remote NAS device. Note that installing Goodsync generally involves using SSH to access the My Cloud and using SSH could void the My Cloud warranty and if used improperly could “brick”/render unusable the My Cloud device.
https://community.wd.com/t/app-goodsync-for-wd-my-cloud-backup-and-file-synchronization/173984
