👋 Hi @KNRT, welcome to the Box Community! Thanks for the question, and allow me to clarify and assist from here.
You cannot let anonymous (not-logged-in) users edit Box files via a shared file link. When a shared link is set to Can Edit, people (i.e., your collaborators) must be logged into Box to edit; anonymous visitors (i.e., People with the link) can typically only view or download.
As outlined in Collaboration Frequently Asked Questions:
Be aware you must have a Box account (at least a Free Individual) to collaborate on content in Box. If you send a collaboration invitation to an individual without a Box account, that individual will be prompted to sign up with Box before being able to access the content.
Why you’re still seeing login required: By design Box requires users to authenticate before making edits so auditability and collaboration controls work (admins can enable/disable edit shared links, apply Shield policies, etc.). Editable file links will prompt people to log in to allow tracked editing.
If you have any other concerns, please feel free to reach out.