Your code isn't working because c:/ or d:/ is totally wrong for linux just use /mnt/c or/mnt/c
From your local windows10-ubuntu bash use this command:
for download:
(from your remote server folder to d:/ubuntu) :
scp username@ipaddress:/folder/file.txt /mnt/d/ubuntu
Then type your remote server password if there is need.
for upload:
(from d:/ubuntu to remote server ) :
scp /mnt/d/ubuntu/file.txt username@ipaddress:/folder/file.txt
Then type your remote server password if there is need.
note: I tested and it worked.