In order to get Backup Radar to successfully monitor your BackBlaze backups, you will need to login to your BackBlaze portal and direct the backup summary emails to your Backup Radar mailbox.
The process for enabling the backup summary emails is detailed in the below KB article (Please set the Frequency of these reports to Weekly):
Please note that you will need to set the schedule for these backups in Backup Radar to Weekly.
However BackBlaze only allows these reports to be sent to the registered email address. You will need to redirect the Backup Summary emails to your Backup Radar mailbox (Please note these cannot be forwarded as this can change the HTML structure of the email).
Alternatively you could change the registered email address to a distribution group and add you Backup Radar email address to this distribution group.