Adding a user doesn't create an account so much as send an invitation — the person you name finishes the job themselves, and there are a couple of one-way doors worth knowing about first.
1
Filling in the invite
Add User asks for a name, an email, a phone number and at least one role. The email is the part to slow down on: it's where the invitation goes, and it can't be changed afterwards — the field is read-only once the person exists, so a typo means removing them and starting again. Everything else is editable later. You can't put someone into a team from this dialog either; that's done by opening them again afterwards, which is worth knowing if you're setting up an agent who needs to be in the round-robin. See Roles and what they open for choosing the role, and Teams for the rest.
2
What happens after you press Create
They get an email with a link that's good for seven days, and they set their own password when they follow it — you never see or choose it, and there's nothing to hand over. Until they do, they sit in the table as Invited (pending registration), which you'll find by expanding their row rather than in the Status column. There's no resend button, so if the invitation never lands — wrong address, spam folder, expired link — the way through is to remove the person and add them again, which sends a fresh one. Check the email carefully before creating: it's the one field you can't correct afterwards.