To provide a person or company with access to your “Company profile” you need to setup a Customer card and Create a User account for them.
First you need to setup a Customer card, this will create a profile for the contact details including Billing and Delivery addresses.
Once you have done that you then need to send them an invite to be able to log in. The person accessing your account may not be the same address that the quotes/confirmations and invoices go to so you have the ability to change that here.