@Keneda if i understand correctly @FelixTC want to install samba server on his phone, and other topics are about using file manager as samba client.
I'm also attempting to install samba, but it's hard, you can't use apt install more here https://askubuntu.com/questions/1271175/ubuntu-touch-how-do-i-apt-get-install and i tried to do this trick with sudo mount -o, remount,rw / but i don't recommend it. In my case it broke only thing which you can use to run apt install - Libertine Containers. In those container i was able to install samba and configure it, but for now i cannot connect to it, even using localhost 😕