“Focusrite” is the brand name.
“Scarlett Solo” is the audio interface unit (the red and black box).
“Scarlett Solo Studio” is a bundle that includes the “Scarlett Solo” interface, a “CM25 MkIII” microphone, “HP60 MkIII” headphones, and a couple of cables.
Before launching Audacity, ensure that the microphone and headphones are plugged into the interface. It is best to turn down the three volume controls on the front of the interface before plugging in or unplugging things.
Connect the interface to a USB 2 socket on your computer.
Ensure that the “48 v” button on the front of the interface is pushed in (so that “phantom power” is turned on for the microphone).
Ensure that the “DIRECT MONITOR” button is pressed down on the interface (so that you can hear the microphone through the headphones).
If you have a “pop shield”, it should be positioned between your mouth and the front of the mic. The front of the mic is the side with the Scarlett logo.
Position yourself so that your mouth is about 30 cm from the mic.
Speak loudly and clearly towards the microphone, and slowly turn up the level of the left hand “GAIN” control. You should see a “halo” LED light start to light up as you speak. That indicates that the interface is receiving a signal from the mic. Gradually increase the level until it flashes yellow, but not so high that it shows any red. If the halo light shows any red, the input level is too high and you need to turn it down a bit.
Carefully adjust the headphone level (the big knob on the front of the interface) so that you can hear your voice through the headphones.
When that’s all set, launch Audacity.
In the Device Toolbar, select the focusrite for both playback and recording.
Set the “number of channels” to “1 (mono)”. This is required when recording one microphone from the scarlett solo.
Make a test recording.
What does the waveform look like? You are aiming for a blue waveform that is about half the height of the track. If necessary, adjust the recording level slider in Audacity (see: https://manual.audacityteam.org/man/mixer_toolbar.html)