Although your storage buckets are completely private and partitioned from all other users on the Wasabi service, the Amazon S3 standard for storage bucket naming requires unique storage bucket names across a S3-style object storage service such as Wasabi. This means that if someone else on the service has already named their storage bucket “test”, that name will not be available to other users. You may wish to name your storage buckets with some unique identifier. Many storage applications will do this for you (create a bucket name with uniqueness per users).
On the topic of naming syntax, Wasabi follows the S3 standard naming rules described in the S3 documentation.