I don't use OPENXML often but knowing XPath makes this sort of thing pretty easy.  Here I'm using a variable for the XML so that you can copy/paste this to see how it works. This query:
DECLARE @XML AS XML, @hDoc AS INT, @SQL NVARCHAR (MAX)
--SELECT @XML = XMLData FROM dwstage.[dbo].[OFSXMLFiles]

SET @XML = '
<appt_links>
<appt_link>
<Field name="ResourceID">38</Field>
<Field name="FromActivityID">4545</Field>
<Field name="FromActivityDate">2017-12-08</Field>
<Field name="FromActivityRouteID">663</Field>
<Field name="ToActivityID">4546</Field>
<Field name="ToActivityDate">2017-12-08</Field>
<Field name="ToActivityRouteID">663</Field>
<Field name="Link Type" />
</appt_link>
</appt_links>';

EXEC sp_xml_preparedocument @hDoc OUTPUT, @XML

SELECT xmlAttrib, xmlTxt
FROM OPENXML(@hDoc, '/appt_links/appt_link/Field',1)
WITH
(
xmlAttrib nvarchar(30) '@name',
xmlTxt  nvarchar(30) '(text())[1]'
);

Returns:


xmlAttrib                 xmlTxt
------------------------- ---------------
ResourceID                38
FromActivityID            4545
FromActivityDate          2017-12-08
FromActivityRouteID       663
ToActivityID              4546
ToActivityDate            2017-12-08
ToActivityRouteID         663
Link Type                 NULL


All that's left to do is pivot these results. Here's how you do it, I only had time for a couple columns but this should be enough to help you across the finish line. 

with x as
(
SELECT xmlAttrib, xmlTxt
FROM OPENXML(@hDoc, '/appt_links/appt_link/Field',1)
WITH
(
  xmlAttrib nvarchar(30) '@name',
  xmlTxt  nvarchar(30) '(text())[1]'
)
)
select 'ResourceID'  = max(case xmlAttrib when 'ResourceID' then xmlTxt end),
   'FromActivityID' = max(case xmlAttrib when 'FromActivityID' then xmlTxt end)
from x;

Returns

ResourceID       FromActivityID
--------------------- ------------------------------
38                      4545

(please forgive the sloppy formatting, the new SSC forum controls trip me up from time to time)