I think yes, that is what the Fathers meant; salvation could only occur in and through the Catholic Church. This was affirmed by a number of councils and Papal statements which effectively stated everyone outside of the boundaries of the Church is going to hell, with unbaptised infants going to limbo.
Vatican II softened the line a bit by opening the possibility for salvation of those outside the Church, but many Catholics still firmly believe in “Extra Ecclesiam Nulla Salus” in its most strong sense (no hope for those outside of the Church), from what I’ve seen and encountered here.
Perhaps the most negative formulation is that of Eugene the IV:
“The most Holy Roman Church firmly believes, professes and preaches that none of those existing outside the Catholic Church, not only pagans, but also Jews and heretics and schismatics, can have a share in life eternal; but that they will go into the eternal fire which was prepared for the devil and his angels, unless before death they are joined with Her; and that so important is the unity of this ecclesiastical body that only those remaining within this unity can profit by the sacraments of the Church unto salvation, and they alone can receive an eternal recompense for their fasts, their almsgivings, their other works of Christian piety and the duties of a Christian soldier. No one, let his almsgiving be as great as it may, no one, even if he pour out his blood for the Name of Christ, can be saved, unless he remain within the bosom and the unity of the Catholic Church.”
The most positive is in the CCC:
"How are we to understand this affirmation, often repeated by the Church Fathers?335 Re-formulated positively, it means that all salvation comes from Christ the Head through the Church which is his Body:
Basing itself on Scripture and Tradition, the Council teaches that the Church, a pilgrim now on earth, is necessary for salvation: the one Christ is the mediator and the way of salvation; he is present to us in his body which is the Church. He himself explicitly asserted the necessity of faith and Baptism, and thereby affirmed at the same time the necessity of the Church which men enter through Baptism as through a door. Hence they could not be saved who, knowing that the Catholic Church was founded as necessary by God through Christ, would refuse either to enter it or to remain in it.336"