I downloaded SeedDMS to see what the setup looked like, but the documentation seems a bit… absent. I don’t know where you got that installation guide because I can’t find it myself.
The documentation you shared also seems to assume you’re connected with SSH to a self managed server, which makes the instructions hard to apply to web hosting.
It may be possible to install it here with some difficulty (barring any further limitations or bugs in the software itself).
However, I can’t encourage hosting this with us. We provide a website hosting service, and only provide space for website content. File hosting, including document storage/archival, is not allowed.
So I would recommend to find a document management solution that does support your software and your use case.