By ticking allow access to 'My Quotes', you are giving the user access to the 'My Quotes' section, meaning that they can create and edit quotes if 'Your Price' is enabled, otherwise providing view only access to existing quotes.
By ticking allow access to 'My Quotes', you are giving the user access to the 'My Quotes' section, meaning that they can create and edit quotes if 'Your Price' is enabled, otherwise providing view only access to existing quotes.