Try looking in the log file of deluge: ~/.config/deluge/deluged.log

can you check in the logs for any errors/exceptions?
the logs are located in ~/.config/deluge/

Does the webui connects to the daemon?
Do you see anything in the preferences? If no, and there is no data (and no plugin is enabled) then you to connect to the daemon.

redirect stdout: pipe it to more/less: i used the connect command as my port is non-standard.

I tried what you wrote and was able to scroll through the entire list (162 torrents). Tested on an ubuntu server, with pipe to less/more, redirection of output to a file and view it from the console-ui itself. Also, from Windows version of deluge as a thin client to the ubuntu server and got everyth...

After adding, the plugin page shows: The AutoAdd plugin is enabled however there is no WebUI preferences page implemented yet for this plugin. In the meantime please use GtkUI preference page to configure this plugin. How to configure? I need a detailed step, thanks~ http://dev.deluge-torrent.org/w...

Did you entered "/deluge/" to the base section in the webui config file (web.conf)?
If not, do it, and restart the webui process

did you filled the auth data in the client? to connect remotely add another server and don't forget to enter the username and password from the auth file. basically you should add another user to the auth file: username:password:auth-level - for example: djlegolas:myawesomepassword:10 next, restart ...

in both the gtk and web ui's you can choose which files to download.
can you please add a screenshot and what version are you running on?

under which user does deluged runs when you use the systemd service? if it's a system user, try to look for the log under /var/lib/<user_name>/.config/deluge/deluged.log if it's a regular user, try to look for the log under that user's home dir (usually /home/<user_name>/.config/deluge/deluged.log