To add new admin users to ScaleXP invoicing, go to the ScaleXP Invoicing Dashboard:

app.scalexp-invoicing.com/
 

Click "Manage Users" in the bottom left, under your company name.

You will then have the option to "Add Users" - click to "Invite User" to your account.

Remember, you only need to add a user if they need to access the admin dashboard.  All users added in this way have admin and dashboard access.