How to restrict group node access to a user/member of an group?
It seems to me that, for what you're trying to achieve, you do not need the "Page access" module. Instead only using the Group module it should be possible to get it to work.

Some basics about the Group module to be aware of:


Make sure you enable gnode, a submodule of the Group module.
For each group type you need to define the appropriate permissions (view, edit, delete, etc) for the various Content Types.
Every group can have users, roles and permissions attached to it (refer to "What are the various roles supported by the Group module?" for more details about that).


It seems that you would want to grant access to what, in Group, is called "Members". But you woudn't allow access to "Anonymous" (site visitors that are not logged it). However, you also need to think about which access you want to give to "Outsiders" (=  logged in users who are not a member of a group).

With the above in place, it's just a matter of assigning a node to a Group. So if the gnode submodule is enabled, you should be able to do so via a group-related field that will be shown on the node edit form, via which you can then select the appropriate group

More info

Refer to "How to create collections of content that can be accessed by users with various access levels?" for more  info about all this.