- Login to WordPress dashboard and head to Plugins --> Add New. Search for the "Restrict Author Posting" plugin and install it. Once installed, activate the plugin by clicking "Activate Plugin"
- Head to User --> All Users. Select a user you want to limit and click Edit
- Scroll down to the "Restrict the categories in which this user can post to" section. Mark the categories that you want to limit. In order to avoid limited users accessing medias from other users you can also check the "Restrict using his/her own file in Media" option.
- Once you are done, scroll down to the bottom and click Update User button