No. Featured, Public, or any workspaces shared with you will be available for viewing after you log in. These do not require a FireCloud Billing Project or Google Billing Account to view. However, to compute on data within these workspaces, you must clone them. Cloning or creating a workspace requires access to at least one FireCloud Billing Project. Note, if another FireCloud user shares a workspace with you, granting you WRITER access, you can compute within that workspace.
If you want to create and clone workspaces, you will need access to a FireCloud Billing Project. All of your options for doing this are described here.