PSOhub will not systematically synchronize all your contacts and companies. It is only when you create a project from a Deal, Contact or Company in HubSpot that their related contact(s) and company will be brought over in PSOhub.
Furthermore when creating a project from a deal, any contact related to the company of the deal will also be created in PSOhub.
Finally, any changes made to the name and/or address of a company in HubSpot will also sync with the corresponding company in PSOhub.
IMPORTANT NOTE: There must be NO coma or apostrophe characters in the name of the contact or the company. This may prevent the invoice from going through to your financial software if you are leveraging the integration of PSOhub with your financial software.