As per the issue description mentioned above, save as Adobe pdf option isn't available in MS Word after update, is that correct?
Try rebooting the machine once if you haven't already and check if that helps. Also, check if you are getting this option in other Office 365 applications.
Also, let us know dot version of Acrobat and the operating system installed on the machine? You may refer to the steps given in this link on how to check the version in Acrobat: Identify the product and its version for Acrobat and Reader DC
Let us know if you need any help.