Can users in a group access a file that is in another user’s home directory?

I have 3 users A,B and C inside a group ‘admin’. I have another user ‘D‘ in whose home directory, there is a project folder. I have made D as the owner of that folder and assigned ‘admin’ as the group using chgrp. Group and owners have all the permissions, but still A,B or C are unable to access the folder. I have two question :