HTTP_REMOTE_USER SSO using Remote User Nginx does not work

Hello Seafile Community Forum, I tried the Seafile Community Edition Version: 7.0.5 to run through the WAF of our Sophos Firewall. My question is how I can evaluate the auth header that the firewall generates in Seafile and Nginx.

In the “Seafile-manual/deploy/SSO using Remote User” is stated edit “configfile conf /” the parameter “ENABLE_REMOTE_USER_AUTHENTICATION = True” must be activated.

Unfortunately I have not found any information about what I have to configure on the Nginx web server.
I would be very grateful for a little help.