Have you checked the options table to make sure that your “home” and your “siteurl” are both set to https://onepagewebsite.org/dwp
You may also have to SAVE your permalinks structure again, this will rewrite your .htaccess file for you.
After you make these changes, your sub-directory website should show up correctly.
You may also want to review this page:
https://codex.www.ads-software.com/Giving_WordPress_Its_Own_Directory
You can install WordPress in your root and install other WordPress installations in sub-directories without issue on MOST hosting company servers.
Good luck.