I want to do this kind of transfer.

host/client A:
     dir:
          - file a
          - file b
          - file c
          - file d [host B][download]


host/client B:
     dir:
          - file a[ host A] [download]
          - file b[ host A] [download]
          - file c[ host A] [download]
          - file d 

Also, I am not looking for syncthing, I need something which syncs meta data(not sure if this is the right word) not the actual files., and option to download individually or as per selection and run in background like KDE CONNECT.