Augustine wrote about the symbolic character of the Eucharist as a sign of unity, but this does not discount the Real Presence.
Augustine clearly believed in transubstantiation. Here are some things he wrote about the Eucharist:
"Christ was carried in his own hands when, referring to his own body, he said, ‘This is my body’ [Matt. 26:26]. For he carried that body in his hands" (Explanations of the Psalms 33:1:10 [A.D. 405]).
"I promised you [new Christians], who have now been baptized, a sermon in which I would explain the sacrament of the Lord’s table. . . . That bread that you see on the altar, having been sanctified by the word of God, is the body of Christ. That chalice, or rather, what is in that chalice, having been sanctified by the word of God, is the blood of Christ" (Sermons 227 [A.D. 411]).
"What you see is the bread and the chalice; that is what your own eyes report to you. But what your faith obliges you to accept is that the bread is the body of Christ and the chalice is the blood of Christ. This has been said very briefly, which may perhaps be sufficient for faith; yet faith does not desire instruction" (ibid., 272).
"Nobody eats this flesh without previously adoring it" (Explanation of the Psalms 99).
"He took flesh from the flesh of Mary . . . and gave us the same flesh to be eaten unto salvation. . . . We do sin by not adoring" (ibid).