Does Collector for Windows allow uploading PDF documents to features? Currently I can only attach media files such as JPG or MP4.
The help documentation below states that images and videos are currently supported as attachment types in Collector for ArcGIS on Windows:
Work with attachments—Collector for ArcGIS | ArcGIS
There is also an idea that is currently proposed on our Ideas Site to allow other attachment types in Collector: ArcGIS Idea - Collector support for other file and hyperlink types
If you agree with the idea, please feel free to log in and promote it. Adding your own use case to the comments can help build a clearer user story for other attachment types. Let me know if you have any questions.