When a person who does not meet the viewing conditions accesses a manual with referrer URL restrictions, "Access to the target is restricted" is displayed.
What viewers can check
When accessing a URL copied from a portal site or other web page using a browser, instead of copying the URL, check if the content can be viewed by clicking the link within the web page.
What Teachme Biz administrators can check
"Access to the target is restricted" is displayed when accessing from a path other than the specified web page while referrer URL restrictions are in place.
If there is an inquiry from a user, verify that the referrer URL is set correctly and instruct them to access from the specified referrer (web page).
Related: Restrict access with a specific referrer URL or password (Web Browser)
https://teachme.jp/8/manuals/10033436