I'm using the File Entity module, and it lets me modify the configuration settings, adding a few fields to a file type, but I can't seem to figure out how to get the custom fields I created to show up in the add content screen. Only the Alt text and Title values show up. What am I missing?
The fields aren't on the add content screen they are on the add file screen (because they are fields on the file entity).
So if you add files via the file/add page you can fill out those fields.
The media module has a feature so that when you upload a file to a node then it pops up the edit form to edit the fields on that file.
So you upload the file then fill out the extra file fields in a 2 step process and then save the node.
I was also looking for that functionality, and found this module does exactly that: File Entity Inline
This module aims to provide the ability to edit File entities inline, as part of another form (such as nodes). This should enable the ability for reusable and site-wide editing of file properties, such as description, alt text, captions, bylines, etc.
In Drupal 8 you can archive this with core elements/modules.
- activate the core module file_entity
- in your file type settings /admin/structure/file-types/manage/image add the extra fields a user should be able to use
- in your contenttype (admin/structure/types/manage/CONTENTTYPE/form-display) choose the Widget "Editable file" for your image field
If you create a new node, you will be able to edit the extra fields of your image in a popup after clicking "Edit"