Hi Candy,
Good day! Welcome to Q&A forum.
Please the following steps to add the Document ID as a Footer to word document.
1.Sign in the Document library as an admin
- Open the word document in app
3.Go to the Insert tab, click on Footer menu, and then select Blank option
4.Select the [Type here], click on Quick Parts menu, and then select Document Property and select Document ID Value.
5.Close Header and Footer and save it
6. When you open the word document again, you will find that the Footer has been set successfully.
Similar issue post for your reference:
How to insert Sharepoint Document ID in a document (Word, Excel...)? - Microsoft Q&A
Hope these information helps.
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