How to determine if excel is 32 bit or 64 bit

Try this

=INFO("OSVERSION")

You may use conditional compilation:

#If VBA7 Then
   Private Declare PtrSafe Function FindWindow Lib "user32" Alias "FindWindowA" _
                                       (ByVal lpClassName As String, ByVal lpWindowName As String) As LongPtr
   Private Declare PtrSafe Function GetWindowLong Lib "user32" Alias "GetWindowLongA" _
                                       (ByVal hWnd As LongPtr, ByVal nIndex As Long) As Long
   Private Declare PtrSafe Function SetWindowLong Lib "user32" Alias "SetWindowLongA" _
                                       (ByVal hWnd As LongPtr, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
   Private Declare PtrSafe Function SetLayeredWindowAttributes Lib "user32" _
                                       (ByVal hWnd As LongPtr, ByVal crey As Byte, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long
   Public hWnd                     As LongPtr
#Else
   Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
                                       (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
   Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" _
                                       (ByVal hWnd As Long, ByVal nIndex As Long) As Long
   Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" _
                                       (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
   Private Declare Function SetLayeredWindowAttributes Lib "user32" _
                                       (ByVal hWnd As Long, ByVal crey As Byte, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long
   Public hWnd                     As Long
#End If

Private Const GWL_EXSTYLE = (-20)
Private Const WS_EX_LAYERED = &H80000
Private Const LWA_ALPHA = &H2&

Private Sub UserForm_Initialize()
       Dim bytOpacity As Byte
    bytOpacity = 220 ' variable keeping opacity setting
    hWnd = FindWindow("ThunderDFrame", Me.Caption)
    Call SetWindowLong(Me.hWnd, GWL_EXSTYLE, GetWindowLong(Me.hWnd, GWL_EXSTYLE) Or WS_EX_LAYERED)
    Call SetLayeredWindowAttributes(Me.hWnd, 0, bytOpacity, LWA_ALPHA)
End Sub

You are welcome.