Can't send file because "owned by different user"

I’m trying to send a file from my PC to a device (both running Linux). Both are connected to my tailscale account and are appearing on Machines as connected. But when I try to send a file I get:
“can’t send to : owned by different user; can only send files to your own devices”

What does this mean? I’m the only user. ssh works fine.

I found an answer on this twitter thread:

“Yes the device must not be tagged to be able to use Taildrop
Currently there is no way for tagged devices to use taildrop”

It’s mentioned on the page as well:

“You cannot use Taildrop to send files to and from nodes you have tagged.”