How to install flash player on Opera Browser linux:
- Open this link https://get.adobe.com/flashplayer/ on opera browser.
- Choose “.tar.gz for linux” and click download.
- Unpack/Unzip the downloaded file, you will get folder “flash_player_ppapi_linux.x86_64”
- Install via “sudo apt install” or via “synaptic package manager” pepperflashplugin-nonfree
- Copy all the files in the folder “flash_player_ppapi_linux.x86_64” to “/usr/lib/pepperflashplugin-nonfree” by open folder as root.
- Restart your browser.