Have installed 3 times STMANI3 on Linux Mint 19.3 Mate 64-Bit computers successfully!
Installation on 32-Bit computer fails with the x86_64-linux-gnu problem.
Installation on Ubuntu Studio 20 is starting the STMANI-GUI.
It is complaining about missing restore-trash
sudo apt-get install trash-cli
does not help.
I leave that open.