I'm using transmission-remote v2.92 and I read in this forum cookies can be used by transmission-remote just by putting a "cookies.txt" file in transmission settings directory (usually /var/lib/transmission).
I did it but its not working. I used the file "cookie.txt" and also "cookies.txt" but its not working. The format of "cookies.txt" is a "Netscape HTTP Cookie File". it look like something like that :
Why do you need transmission-remote to use cookies? It only uses libcurl to communicate with transmission-daemon (or some GUI client) and never with the tracker, so cookies are irrelevant there. What you probably want is for transmission-daemon (or some GUI client) to use cookies, and for this to happen you need to place the "cookies.txt" file next to settings.json.
I'm not entirely sure that it'll help but you could try setting TR_CURL_VERBOSE environment variable (to any value) and running transmission-daemon (or some GUI client) from terminal in foreground mode to see the output. It might also help if you expand on that "not working" statement, specifically what you expect to happen. Just an FYI, Transmission only reads this file and never writes it.
P.S. Please don't create support issues on GitHub. People here will either answer or they won't; on GitHub, this kind of questions won't ever (?) be answered.
I'm sorry to repoen that again but finally I wanted to give a try to TR_CURL_VERBOSE. So, I enabled that environment variable and I could see the requests to download the torrent. No cookies was found into the header despite "cookies.txt" file was created in /var/lib/transmission (where my settings.json sit).