I'd recommend using Restic (https://restic.net/), it supports backing up to Backblaze B2 and generally is the best and most innovative backup tool I've ever used.
And if you'd like something more accessible for regular desktop usage, check out Relica which makes use of restic under the hood. Author is Matt Holt, the guy behind Caddy server.
Backblaze has a Restic howto: https://help.backblaze.com/hc/en-us/articles/115002880514-Ho...