The Holy Father does, as is his wont, use a very vivid turn of phrase; and he also expresses himself in the negative rather than the positive.
But his essential message for those who frequent the Sacrament is: approach the Sacrament with a genuine shame, a genuine sense that you have done something wrong. The first prompt of conscience that draws you to the Sacrament is a good - but try to go further, deeper in responding to that first prompt.
... You have only gone to confession to carry out a banking transaction or an office task. You have not gone to confession ashamed of what you have done. You have seen stains on your conscience and have mistakenly believed that the confessional box is like the dry cleaners that removes those sins. You’re unable to feel shame for your sins.”The shame being referred to here is of a very particular character. It is a response, by the person themselves, to a recognised wrong that they have done. It is not what might be expressed by the word "stigma" - that is, a shame imposed from outside by others or by society, a shame that has the effect of limiting the freedom of the individual rather than expressing it.
A reflection on what constitutes a healthy sense of shame is important in times when much of our society, lacking an objective sense of right and wrong, would do away with the notion of shame altogether.