Hello! Unfortunately I have to look for help here.. I have ISPConfig 3.2.12 and it fails with WordPress. I upload it via FTP, the DB is set up and the installation starts via www.domain.at. But everything is displayed as a kind of HTML and not correctly as it should be. I have already tried many PHP settings in ISPConfig but without success. When I installed it, I see the demo page but there is also an error and when I log in to the backend everything is only visible as "HTML", which is not how it should be. I run it with an Nginx proxy manager including SSL LE and port 80 works. Does anyone have any advice or is it WordPress - I'll get in touch there.
Did you upload it as user of that website? What are onwer, group owner and permissions of the files? Are the files correctly extracted from the wordpress zip and directory structure is intact? That looks line web server configuration error, instead of rendering the HTML it displays the HTML code. This is unusual, have you altered configurations?
As you are using Nginx, you must set WordPress specific rewrite rules in the Nginx directives field of the website: https://forum.howtoforge.com/threads/ispconfig3-nginx-wordpress-perm-urls.56876/#post-277319
