PSOhub will not systematically synchronize all your contacts and companies.
It is only when you link the account to the opportunity, that the contacts linked to the account that will be synchronized in PSOhub.
Furthermore when creating a project in PSOhub and link this to the opportunity any contacts linked to the opportunity will follow, also contacts who are not linked to the opportunity but are linked to the account will be synchronized 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.