Buy display TFT screens with Arduino without the shield

I've recently brought a TFT screen from Buy Display

which I'm looking to use with the Arduino Mega, to do this the datasheet say that logic level is 3.3V which means i need a logic level converter. So I've connected the Arduino Mega to the logic level converter then onto the screen SPI pins on the screen.

they have an Arduino Shield that they also sell:

at the bottom of the page is an Arduino library for driving the graphics chip with the shield, from what i can see all the shield is just a logic level converter for the screen, I've got this from the schematics and my understating of Arduino logic.

So will the library that they supply with the shield work with the set up i have created? I cant see why it wouldn't but when i connect it all up the screen is not working, its black but their is data on the pins on both side of logic level converter, I was using one of Buy Displays Arduino Mega examples that come with the library on the shield page, I've made sure I've changed the CS but its still not working and i cant see why it wouldn't work.

You have bought an expensive display.
So why not buy the ready-made Adapter Shield that is designed for it?

It looks as if you have bought the Parallel version of the display.

The RA8875 controller can be configured for SPI. I would have to study the EastRising documentation. There are normally solder-bridges to configure.
BuyDisplay configure them for the display that you have asked for.
I have used an 800x480 RA8875 display via SPI on a Uno with the Adapter shield (and directly with 3.3V Arduinos).

I have probably used my own code. So I am not sure about EastRising/BuyDisplay code.