Does the Audio-Technica AT2020 need a booster into the Audient EVO 4?
Yes. At speaking level the AT2020 needs about 37 dB, and the EVO 4 publishes 58, so 21 dB of gain is spare. An inline booster is not what this pair is missing.
The Audio-Technica AT2020 has enough preamp on the Audient EVO 4 for a normal speaking voice. You do not have to add a box in front of it.
Audio-Technica rates the AT2020 at -37.0 dBV/Pa, the voltage from a loud 94 dB tone at the grille. A speaking voice is closer to 85 dB, so the preamp still has to find about 37 dB to land near −9 dBV. That −9 dBV figure is just a tracking level: high enough to use, with space before the converter clips.
Set the knob for the voice you actually record and leave a little travel for plosives, instead of pinning it because the spec sheet has a higher number. A booster on a chain that already has about 21 dB spare only adds a box. Most of those boxes also use the phantom power themselves, which will silence a condenser.