In that case, an external audio interface is your best solution. Then get a mic and you can also do vocals (or get somebody else to do them if you can't sing).
Assuming you have a windows PC and not a Mac, then you'll get lowest latency from using the ASIO drivers for the Focusrite. Which means that you'll need to use the Focusrite (or whatever interface you get) for inputs and outputs when using your DAW. Windows can only use one ASIO driver at a time. So any speakers your headphones you use will need to be plugged into the interface. You may currently be using the computer's own sound card for sound output at the moment.
The XLR connections from the Line 6 will be at at line level, not mic level, so whilst the Focusrite has two 'combi' inputs that have both XLR and TRS jack connections, the XLR portion is mic level and the jack connection for line level inputs, so you'll need a couple of XLR to TRS jack leads.
Last edited by Simon Barden; 15-12-2020 at 08:03 PM.