V_Make reports several issues after setting up Discourse: (1) accessing the subdomain leads to an empty directory listing (e.g., cgi/bin), (2) only one browser can access the instance while others fail, and (3) moderator invitation emails return Error 404 when clicked. mpalmer clarifies these are not questions but symptoms needing diagnosis, asking for details on webserver configuration, browser specifics, and relevant logs. fefrei suggests a possible match with a known issue involving inconsistent page loading (linked here), but V_Make replies that their problem wasn’t accurately described. fefrei urges V_Make to unaccept the answer if unresolved and respond to mpalmer’s diagnostic questions — including sharing the instance URL — to enable further debugging.
Wait, did that solve your problem? If not, you should probably un-accept my answer and reply to the questions @mpalmer posed. (In addition, posting the URL of your instance can help us to debug this.)