No.
Contacts added to the directory will only have access once you grant it to them. To do this, you need to add them to a project and check the "Access to the platform" option in the project settings. You can revoke their access at any time by unchecking the boxes.
The directory in your environment serves as an address book and includes all the contact people you need to keep on hand. You can link these contacts to companies that you also create in your directory.
Useful Tips : It is not mandatory to create contacts from the directory in order to add them to a project. You can do this directly from the project settings by clicking "+ add" in the dropdown list of clients/participants in the project.