I’m a reeeeal newbee - but would like to report what happened to me:
I have downloaded Volumio 2.245 and installed as described in the documentation and so on. When chosing “Plugins” there was no option to search the plugins. Meaning: The button “search plugins” appeared on the user interface, but no plugins to search through (which are located usually under the search button).
Various restarts of the system did not help - so I wiped the SD card and installed an older version of Volumio [in my case it was 2.201 (2017-06-13)].
After installing this (older) version the plugin section worked as usually - I was able to install the plugins.
After that, I updated the system to 2.245 (via SYSTEM ==> UPDATE on the user interface) and the plugin search option stayed there and is still working like normal.
I have the impression that this might be a bug.