Data Manager admins can make other users admins.
After the user logs in at https://vulekamali.gov.za/accounts/login, the page homepage will show their username in the notice after "Successfully signed in as ". If they are already logged in, ask them to log out and log back in again to find their username and provide it.
You might also be able to find them in the user list, but be sure to check that their e-mail address is what you expect, in case someone else with a similar name already has an account.
When you have their username, find it in the user list, and click on their username to edit their user account.
Ensure the "Superuser status" and "Staff status" checkboxes are checked, and click Save.