When a consultant configured a Windows GPO for Acrobat Reader DC 2017 in our enterprise, an Adobe ADMX file was used (Acrobat2017.admx). Its 2021, all the Adobe Reader DC installations have auto-updated to 2021.005.20060, and we are updating all the Active Directory ADMX files to the latest versions, except I can't find a newer ADMX file than this for Reader DC. In fact, I cannot find any Adobe ADMX files for any of it's products newer than 2015. Even more bizarrely, Adobe's sites don't even reference ADMX files for configuring their products with GPO's.
Maybe the consultant packaged it, using into in the Acrobat Enterprise Deployment Toolkit. (Be Aware, since the consultant may also not have documented another key fact, that you WILL need an up-to-date redistribution license for Acrobat Reader. )