For the missing library, find the package containing libFLAC.so.8 and install it, or something close and simlink it.
To find which package contains a file, use apt-file. If you don't have apt-file installed already, install it and update its database before using it to search.
Code:
sudo apt install apt-file
sudo apt-file update
apt-file search libFLAC.so
Then install the appropriate package. If it doesn't find it, then its not in your distros repositories.