Addressable LED RBB strip type P9813? needs a sketch

I am brand new to Arduinos and LEDs. I am using an Arduino Mega. I got it to work and learned to upload simple sketches and power a few kit projects that came with the board.

Now I am trying to use it to control a 2 meter 4 wire digital RGB strip (Flex Pixel #FLX775) from Elation Lighting https://www.elationlighting.com/flex-pixel-p40wp.

I have several of these strips installed in my loft by a lighting professional, powered by a DMX controller, but I have to boot up a laptop to run the DMX controller every time that I want the LED strips to light up. So to simplify this, I am trying to build an Arduino to do a series of color shifts and chases that will go on every time I turn power on to the lights and board.
I wired it up according to a NeoPixel diagram I found here: Basic Connections | Adafruit NeoPixel Überguide | Adafruit Learning System
I found the FastLED library and chose the simple Blink sketch. I tested it and my wiring out on NeoPixel strip and it worked fine.
By trial and error, I found out that if I put // in front of the default line of code that tells the program which LED strip is being used: [FastLED.addLeds<NEOPIXEL, DATA_PIN>(leds, NUM_LEDS); // GRB ordering is assumed], which I gather is the way to make the program ignore it. And then I deleted the // in front of line: FastLED.addLeds<P9813, DATA_PIN, CLOCK_PIN, RGB>(leds, NUM_LEDS); // BGR ordering is typical, that I got my LED strip to blink red, as the sketch is intended.

Now I am looking for a sketch that will control all the 144 pixels in the strip and have them change colors, act as a chase lights or other color effects.
I tried a few other from the FastLED library but none of them did anything. Perhaps, the P9813 that I stumbled on only works for the simple Blink sketch?

I would so appreciate any help.

What is your circuit?
How are you powering the LED strip?

How many LEDs total? They need about 0.06A each at full white, do the math and make sure the supply is appropriately sized.
500mA from the Mega won't cut it.

I have a 5v power supply that is sized for the strip. So now I need to find sketches for this type of LED strip. Can you suggest ones to try?