-> anyone remember how to make Local Upload and Downloads in Sysop mode
-> in PCBoard 15.x?

Use internal protocol.  Try Xmodem/CRC.  When it asks for download path,
do not include the filename, only enter a directory name.  Works for me:

(195 min. left) Main Board Command? d

Enter the filename to Download (Enter)=none? calguide.zip
Checking file transfer request.  Please wait, John ...
Download Time:  3.6 minutes (approximate)
Download Size:  43880 bytes (343 blocks)
Total Will Be:  43880 bytes
Protocol Type:  Xmodem/CRC
File Selected:  CALGUIDE.ZIP
(Ctrl-X) Aborts Transfer

Transfer Successful, John.  (Avg. CPS: 43880)

--- PCBoard (R) v15.4/M 250 Beta