To access the portal and edit listings on behalf of a business that is already registered on the MyListing Portal, you should ask the owner of that account to invite you as a ‘collaborator’. You should not register as a business.
When you have been invited, an account will be automatically be created for you and you’ll be able to submit and edit listings for this business.
You can be a ‘collaborator’ for multiple businesses. You will only need one account as you are able to swap between businesses within your account.