I'm not sure why people are having so many problems with this. I almost didn't try this based on all the feedback here.
I just downloaded the Wiki.js and Postresql 14 containers via the apps page in Unraid and had everything working in minutes. I edited the config.yaml for Wiki.js and changed the db type to postgres and changed the host and password (port and user are defaults). This will not automatically create the wikijs database and will generate unspecified errors when trying to connect in the error log. Therefore, I just downloaded pgadmin, connected to the server with the same info as in the config file, and created a new wikijs database with the postgres user (default) as the owner. The connection succeeded in the error log and noted the database was empty and to complete setup. I navigated to the Wiki.js site and completed the setup. Search and all other functionality work fine.