Is there any link to that video?

It seems that you're not providing an IRIS user... and the app is configured to ask for password. Don't you get the login screen asking for user/password?

Thanks @John Murray for arising this... I was getting crazy thinking I was doing something wrong with a simple webterminal installation. 🤯

Thanks @Theo Stolker It works for me also doing in the way you mention. I think you don't need to include %All role to /terminalsocket... as John mentioned at the end, one easier (but less secure) way would be just to set RW privilegies to %DB_USER or to a specific resource %DB_xxxxxx, associated to the database where WebTerminal was installed.