Upload Website to Server - problems

I am trying to build a website using a template and upload it to a Server. When I do the hugo server command and preview the site it looks fine, but when I just do the hugo command and upload the public folder content via ftp to the server and try to access it online, then I only see the text: http://www.imui.org/

I don’t know what iI’m doing wrong. I know it’s a problem that some people have and I found posts (I cannot posts the links, because new users can only use two links), but the answers don’t help me. I run the command ‘hugo --theme=Foldername’ and I tried the ’ rm -rf public/ && hugo command from the second post, but the latter just does not work. What am I doing wrong?

Here are the files I am working with: https://github.com/Knallberto/imui

I found the answer here: [SOLVED] Hugo Not Rendering CSS but Hugo Server Is
I was just missing an / for the base url.