As an entity within Katapult a user is considered separate to an organisation as so far as their credentials etc are concerned. When you add a new user, they'll be sent an e-mail with a link to allow them to add your organisation to their Katapult user account. If they don't have a Katapult user account they will be able to create one before accepting your invitation. For more detail, refer to the Organisations, Users and Roles guide.
After you click save the new user will be emailed by the Katapult system extending them an invitation to join your organisation. The user will need to click the link in the email whereby they will be asked to login to their own Katapult account. Should they not have a Katapult account they will be asked to create one. The account they create does not belong to your organisation, but your organisation will then be connected to their account in so much as you are providing them permission to access your organisation and its data. If the user happens to be associated with other Katapult organisations or uses Katapult for themselves then they will be able to select your organisation from the selector within the Katapult console.
The user will then be deleted from the organisation. If you decide to re-add this user in future then the user will need to accept a new email invitation as per the steps outlined in the invite section above.
If you haven't already assigned a user a role at the time you invited them to your Katapult organisation, or should you wish to change a users role then follow these steps:
The user will now belong to the new role. They may need to sign out and sign in again for the change to take effect.