I have a similar problem. I think I followed all the instructions properly and have got to stage:
https://www.typingbytouch.co.uk/Trial/blogWP/wp-admin/install.php
This gives me the 404 error message. I transferred all the unzipped wp files to a new sub-directory so that the material would not be cluttered up with anything else. I changed the sample config file as instructed.
Does it matter that I have used a sub-directory of a sub-directory?
I up-loaded stuff via ftp for which I type in a password. I am hosted by 1and1.co.uk. But I don’t need a password to access via http.
My developing web page is at https://www.typingbytouch.co.uk/Trial/, written in Microsoft Publisher, which does not help me an the blog part. So I am planning to add the blog part using WordPress.
Is there anything wrong with this approach?
bobcity