Id' need to install DOCUMENT SERVER into a server with PLESK ONYX on.
With Community Server it seems to be possible:
"If you need to change the port for Community Server, you can do that using the -p command.
E.g.: to make your portal accessible via port 8080 you will need to use the following command:
sudo docker run -i -t -d -p 8080:80 onlyoffice/communityserver"
What about DOCUMENT SERVER?