VBA code getting Compile error:

Did you try doing what the error message told you to do?

See here: http://www.jkp-ads.com/articles/apideclarations.asp

Snippet from link:

Conditional compiling

If your code needs to run on both 32 bit and 64 bit Excel, then another thing to do is add conditional compilation to your VBA.

Microsoft devised two compile constants to handle this:

VBA7: True if you're using Office 2010, False for older versions

WIN64: True if your Office installation is 64 bit, false for 32 bit.

Since the 64 bit declarations also work on 32 bit Office 2010, all you have to test for is VBA7:
#If VBA7 Then
Private Declare PtrSafe Function GetDeviceCaps Lib "gdi32" (ByVal hDC As LongPtr, ByVal nIndex As Long) As Long
#Else
Private Declare Function GetDeviceCaps Lib "gdi32" (ByVal hDC As Long, ByVal nIndex As Long) As Long
#End If

And then in the routine where this function is put to use:
#If VBA7 Then
Dim hDC As LongPtr
#Else
Dim hDC As Long
#End If
Dim lDotsPerInch As Long
'Get the user's DPI setting
lDotsPerInch = GetDeviceCaps(hDC, LOGPIXELSX)