First of all, you should setup menu to layout: Manage Categories at Frontend of your site.
Second, you should go to Edocman ACL management page and allow access permission to "Manage categories at frontend" with specific Joomla User groups. See more at:
Ok, thank you very much - but unfortunately this is not what I need.
If my customer wants to upload a document in the frontend, he should be able to save not only the title and the document in the same form, but also create a new sub-category here.
The main category (already created) would be "Company".
The subcategory (already created) would be "Business event".
The customer now wants to upload some documents that belong together to a certain event. So he would have to create a new category called e.g. "Event from 12.08.19 in Ulm". Only in this category are the documents.
Now it must go in addition first into the frontend form category go there a new category ?Event of 12.08.19 in Ulm? create - then into the Uploadform - the new category select and then everything upload.
It is not very user-friendly. Can you do anything?
It should be possible to create a subcategory (if needed) directly in the upload form: That would be great!
Choose main category:
Choose or assign a new subcategory: