The context of Pope Francis's "This is not communism, but pure Christianity" in his 11 April 2021 Homily was a description of the disciples's response, a natural response enabled by Jesus who gave them threefold gifts of mercy (peace, the Spirit, his wounds):
And that is what the disciples did: receiving mercy, they in turn became merciful. We see this in the first reading. The Acts of the Apostles relate that “no one claimed private ownership of any possessions, but everything they owned was held in common” (4:32). This is not communism, but pure Christianity. It is all the more surprising when we think that those were the same disciples who had earlier argued about prizes and rewards, and about who was the greatest among them (cf. Mt 10:37; Lk 22:24). Now they share everything; they are “of one heart and soul”” (Acts 4:32). How did they change like that? They now saw in others the same mercy that had changed their own lives. They discovered that they shared the mission, the forgiveness and the Body of Jesus, and so it seemed natural to share their earthly possessions. The text continues: “There was not a needy person among them” (v. 34). Their fears had been dispelled by touching the Lord’s wounds, and now they are unafraid to heal the wounds of those in need. Because there they see Jesus. Because Jesus is there, in the wounds of those in need.
Thus Pope Francis was NOT teaching that the whole society was to live like that.
Secondly, while everyone in the Catholic religious order community have all things in common modeling after Acts 4:32-37, the vow of poverty itself is based on Matt 19:16-22 for responding to the Evangelical Counsels of perfection, which is NOT binding on all Catholics:
[Jesus] also taught certain principles which He expressly stated were not to be considered as binding upon all, or as necessary conditions without which heaven could not be attained, but rather as counsels for those who desired to do more than the minimum and to aim at Christian perfection, so far as that can be obtained here upon earth.
Thirdly, communism implies force, socialism implies ideology, but that is not the correct reading of Acts 4:32, which at the heart is voluntary response (as Pope Francis indicated in his homily as well). The Catholic Answers website article No, the First Christians Were Not Socialists: We are called to be generous, not to abandon private property said:
Nowhere in the New Testament do we find a prohibition against owning private property. We do find the practice of believers placing goods at the apostles’ feet for communal distribution (Acts 4:34-35), but even this generosity is not mandated for all Christians.
Given the persecution of the early Church, it made sense for Christians to share communal property and meet in private homes for worship (1 Cor. 16:19), but those practices are not proof that all Christians are obliged to live this way. If socialism was morally required of Christians we would expect the New Testament to say this or at least mandate a tithe, but as New Testament scholar Craig Blomberg points out, while tithing was commanded of God’s people in the Old Testament, “no New Testament text ever mandates a tithe but rather commands generous and sacrificial giving instead.”
Further, Acts 2:45 does not unambiguously say first century Christians completely renounced private property. The verse literally says of the faithful and their possessions, “they were selling and were dividing them to all” (Gr. hyparxeis epipraskon kai diemerizon auta) rather than “they had sold and distributed them to all.” Luke’s use of imperfect verbs in this verse seems to describe a continuing process of selling extra property and goods in order to support the poor. But in order to do that Christians would have had to retain some private property even after becoming believers.