It is just a chrome extension app. Use Alt + Number to switch tabs.

The default setting of Chrome in Linux uses Alt + Number to switch tabs, while the one in Windows uses Ctrl + Number. But I used to Alt + Number in Windows. That's it.

Google Chrome only allow to add max four shortcuts.

The commands API allows you to define specific commands, and bind them to a default key combination. Each command your extension accepts must be listed in the manifest as an attribute of the 'commands' manifest key. An extension can have many commands but only 4 suggested keys can be specified. The user can manually add more shortcuts from the chrome://extensions/configureCommands dialog.

So, open chrome://extensions/configureCommands and set whether key you like.