failed to Grants a member access to an image

If you are not going to use Keystone, then the shared image support is meaningless—without Keystone, Glance has no concept of an image being owned by anyone at all, and so images are implicitly shared with anyone and everyone.

Now, on to your specific error: You have not defined your credentials in the environment variables (OS_AUTH_USER, OS_AUTH_KEY, OS_AUTH_TENANT, OS_AUTH_URL, and OS_AUTH_STRATEGY; see doc/source/authentication.rst in the Glance source tree). This is likely no surprise, since you state that you intend to not use Keystone. However, the shared images support requires that Keystone be used, as stated above; since Keystone credentials are not provided, it returns a response saying "Authentication required." The Glance client helpfully suggests that you need to set the credentials.

In short: If you wish to not use Keystone, shared images are meaningless to you; you don't need to worry about them, and you can ignore that error. If, on the other hand, you wish to restrict who has access to what images, then you must use Keystone; Glance has no means of determining who you are and what permissions you may have unless you do.