This is a 3.5 inch touchscreen for systems using the BTT CB-1 board- it connects via the included SPI cable to a Manta 4P or Manta 8P MCU, or the Pi4B adapter when combined with the IO2CAN adapter. You also need the IO2CAN when using the CB-1 v2.1.
This screen doesn't support touch functions when used with a CM-4 board, only the CB-1. Use with a CM-4 requires an I2C interface cable which is not included.
Setup information is available at BigTree's github page.