Hi, I’m having the same issue, on the finish installation screen:
https://meta.discourse.org/t/subfolder-support-with-docker/30507/10
The styles & js file load fine, but the images (tada.svg, etc) and the jquery_include.js file 404.
It’s a brand new subfolder install (Docker version) that followed the instructions in the above thread, except I removed the Fastly replace block (not using Fastly) and the command to remove the public symlinked folders.
The Discourse version is 1.7.0.beta10.
Is it a hard requirement that you have a subfolder install? Because it is a much more complex setup, with many more things that can go wrong.
We recommend subdomain in 99% of cases.
Yes, I understand it’s harder, but it can be done 
Any idea what the issue is?
We don’t spend much time supporting it, except when enterprise customers pay us a lot of money to do it. And we tell them not to. 
Apparently there’s a lot of interest and even success since there’s a long how-to thread I linked above. I’ll see if someone has some insight over there as well.
Are you talking only about the /wizard?
You can skip it and config everything in the admin panel, if only the wizard is broken.
There’s also the jquery_include.js file I mentioned. And when I visit other parts of the site, images are missing as well – like the logo & system user avatar
That’s always the case in subfolder installs. You need to go into settings and set your own logos for it.
This ended up being an issue only on vagrant. The subfolder install instructions worked perfectly without a hitch on my production server.