[copy Instagram cookie from browser to phone app]

hi, i have my GF instagram connected to my browser on my Linux pc, the problem is that i want to see direct messages and its not possible on the browser only on mobile phone and i dont know the password but i managed to extract the cookies (sessionid), and now i can login only with this cookie, 

i want to copy this cookie to my Android/Iphone instagram app, how can i do that??

i hope this is the right place for this question :)