ruijt said:

Is it possible to assign a group to a wordpress role like subscriber?

No, but you can designate one or more Default Groups which will be assigned to every new user. Use the "set defaults" link at the top of the "Role Groups" form.

Note, thought, that as of RS 1.3.39, Role Groups cannot be defined on Multisite installations with the "Share groups network-wide" option enabled. This is fixed in the current Role Scoper development code.