Yes, you need to specify the location manually. There are some answers above explaining how to input the correct path.
Regarding the sync feature, I’m afraid is still not working. Syncing any big content to my Android phone still fails. I didn’t check anymore on this issue to be honest, I switched months ago to the media app provided by my NAS. I can at least download a full movie to my phone without issues would have been nice to use Plex to get smaller files though…
