If you are just trying to figure out how to increment your counter then this should get you started. In your case, instead of using an array you would just put the the code to add or increment the dictionary inside your file reading code.
Code:
Private Sub Command1_Click()
Dim arrList(9) As String
Dim dict As Dictionary
Dim i As Integer
Dim intCnt As Integer
Dim varEntry As Variant

    arrList(0) = "AAA"
    arrList(1) = "AAA"
    arrList(2) = "AAA"
    arrList(3) = "BBB"
    arrList(4) = "CCC"
    arrList(5) = "BBB"
    arrList(6) = "BBB"
    arrList(7) = "AAA"
    arrList(8) = "AAA"
    arrList(9) = "BBB"
    
    Set dict = New Dictionary
    
    For i = 0 To 9
        If dict.Exists(arrList(i)) Then
            intCnt = dict(arrList(i))
            dict(arrList(i)) = intCnt + 1
        Else
            dict.Add arrList(i), 1
        End If
    Next
    
    
    For Each varEntry In dict
        Debug.Print dict(varEntry) & " - " & varEntry
    Next varEntry
    
    Set dict = Nothing
    
End Sub