Your Linux device must have the BlueZ Bluetooth stack installed and working before you can use BittyWeb. Try running the command bluetoothctl from a bash shell to ascertain whether it is installed or not and type version to check the version. In general the later the version, the better.
These instructions will help you install the latest BlueZ.
BittyWeb has been tested with BlueZ 5.50 on Ubuntu 16.04
Only Google Chrome can be used with Bitty Web on Linux.
To use Web Bluetooth from Chrome on Linux, you must enable it in Chrome's configuration settings. Go to the URL chrome://flags/#enable-experimental-web-platform-features enable the highlighted flag, and restart Chrome.