Unfortunately no one can recover your data. The encryption key is required to download the files.
That is why it is necessary to keep a copy of the encryption key in a safe place, such as a password manager, and also to periodically check that the encryption key allows you to download the files.
Your data is encrypted using a technology called Server-Side Encryption with Customer-Provided Keys (SSE-C). See Backup file encryption for more details about this topic.
If your question is not listed here, or you have any questions, please feel free to write to us at support@securaebackup.com.