Do I need a voltage regulator to power LEDs?
WS2812B draws 50mA when fully on, with 24 of them, expect 1.2 Amps.
PC USB ports are limited to 500 mA, so they're out. You'll have to use a &quot;USB cellphone fast charger&quot; which is really a 5V 2A power supply with a USB connector on the output.
Since the &quot;charger&quot; already provides regulated 5V, you don't need the regulator for the LEDs.
If you use a 5V micro (as implied by the fact you use the 5V version of the regulator) then you don't need it for the micro either.