Around here the Install Cloud instructions are recommended. Have you upgraded to a recent version of Discourse? The 1.6 version that gets installed with their one-click install is very old. It won't upgrade from the browser, you'll have to log in and
./launcher rebuild app
And then you have to do it again because of an old version of Postgres.
Note that since their one-click install doesn't create swap space, upgrades might fail due to lack of memory. (In the days of 1.6 you didn't need swap if you had 2GB, but upgrades are more memory hungry now. The upgrade worked for me on a clean install, though.
You can check the mail logs for errors. It may be that the welcome message you expect wasn't in 1.6.