I'm having the same issues as Genesis and can't get the 'error' to go away.  There's no place to enter the 'Endpoint' as described here github [dot] com/unaio/una/wiki/Remote-Storage

There is no such configuration option in UNA v.11
Support for other S3 compatible storages as well as Authentication Signature v4 will be available in UNA v.12, we tested implementation using Amazon S3, Google Storage and Wasabi, documentation for remote storage already added, but it's applicable to UNA v.12 only.