FastLED VS esp32-fastled-webserver

I used the examples from here https://github.com/FastLED/FastLED/wiki/Multiple-Controller-Examples

Sweet. Then pretty much any arduino or other microcontroller would take care of what you need. The strips only take one output pin plus power and ground so just about everything will work for driving them. They act like a long shift register so the single pin is all that's needed to load the full strip with whatever patterns you want regardless of the length. You just have to tell it how many LEDs there are in total is all. Check out the FastLED library. You can learn more about it there and/or install the library in the IDE by pressing "ctrl shift I" for windows or "command shift I" for mac and search for it in the upper search area and install it right there. It comes with working examples too so all you would have to do is install the library, load one of the new example sketches that came with it, and probably edit the example to change the NUM_LEDS count to match what you're working with.

Let me know if you need help lifting code from here I think the Union Jack would be amazing:-)

300 LEDs at 60mA gives 18amps so don't expect to power the LEDs via your ESP32! Instead split the power so that one leads to your ESP32 and the other to your strip. If your intention is to have the LEDs display white for long intervals then an 18 amp PSU is what you need. You haven't said how beefy your PSU is but it looks the part. That said, if you are looking to use the led strip to display FastLED patterns you are unlikely to draw more than 10Amps. You will suffer a voltage drop over 300 LEDs. Injecting power at both ends and in the middle should address the issue. Place the capacitor across ground and 5 volts close to your led strip. And if you have it to hand place a 300ohm resistor in line on your data line next to your voltage stepper chip (SN74HCT245N). I have a schematic here to help you out. I see you don't list a voltage stepper. No drama, you may not need it. It's there to boost your data pin out from 3.2 volts to 5 volts ( as recommended by the led datasheet). But hey - 3.2 volts may just be sufficient. Hope this helps and best of luck!