Fill in fields
One person: People → the person → Fields → Edit. The panel shows each field's value; a field marked Ask when inviting that's empty reads Missing, and the person shows under Needs attention (No Employee ID).
When inviting one person: the invite form asks for every field marked Ask when inviting.
Inviting several: People → Invite → Several people. Download the template: a spreadsheet with Email, Name, Role, Tags and a column for each field. Fill it in and upload it (CSV or Excel), or Type them in on a card per person. Columns are matched to fields by name. Check the list shows each person's problems (Employee ID is needed, "Austrlia" isn't one of its choices. Did you mean Australia?) with Use Australia and Fix fields right there. Values are kept with the invitation and given to the person when they join.
Projects, sites and work types: their own create and edit forms have the fields; a project's or site's page has a Fields section; a work type has a Fields button.
Many at once, from a spreadsheet: Settings → Fields → Fill in from a spreadsheet. Upload a list (your payroll's employee list works). People are matched by email; projects by code or name, sites and work types by name. A match by name only is shown for you to confirm. You see every change (Employee ID: — → 104) before Save. Blank cells leave values alone, unless you switch on Clear values for blank cells.
Example: Priya downloads the employee list from her payroll (email and employee number), uploads it in Fill in from a spreadsheet, picks Employee ID for the number column, checks the preview and saves. 18 people get their IDs at once.