To setup B2 as primary storage in Nextcloud you of course need to install NC first. For that, I used setup-nextcloud.php script - it is a nice, quick way of deploying nextcloud on shared hosting. Normally i would recommend setting it up as a docker container, but that will also work for testing. While installing Nextcloud just pick default storage place for now.
Creating bucket in Backblaze
If you don’t already have Backblaze account, you can register here. Backblaze gives 10GB of free storage + 1GB traffic per day for every user.
Note: make sure you select correct region, as of right now, accounts can’t be moved between regions