Just wanted to share my experience, which I believe is the “intended” way for it to work:
If I have a vault entry, it displays the matching vault entry.
If I have no entry, it follows an account-creation workflow.
After filling in the above and clicking a second time on the bitwarden shield a second time, it offers to save the entry:
This does seem reasonable workflow, but as others have said, it really only makes sense if one is on a registration page. And, it probably ought to auto-save the entry as each step is processed to protect against data loss.