Incase Adobe is already installed on your machine simply use ShellExecute API.
Put this on top of all declarations
Public Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hwnd As Long, _
ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, _
ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long
and simply use as
ShellExecute 0&, "open", fileFullPath, 0, "Directory", 0