not in sync: resp=0xbe and programmer is not responding

Hey there,
I'm having trouble with uploading my code to my board. It's not an original Arduino board, but in the manual it says it behaves like an Arduino Uno. (http://www.produktinfo.conrad.com/datenblaetter/1500000-1599999/001525450-an-01-en-8_X_8_RGB_MATRIX_DISPLAY_TREIBER_BOARD.pdf)

However, when I try uploading the code, I get an error:

avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xbe
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xbe

(It repeats until attempt 10 of 10)

I'm using Windows 10, selected Board: "Arduino/Genuino Uno", and when I plug it in, I can select Port: "COM3".

I hope someone can help me here, thanks in advance.

Are you hooking up the DTR lead? The PDF example uses a FT232, but doesn't show using the DTR lead.

Sorry, but what exactly does that mean? I'm new to arduino

Sorry, but what exactly does that mean? I'm new to arduino

Tell us how you are connecting the ST1149 board to your computer.

The example shows Ft232:

"We use FT232 program downloader(ST1125) connect the board
to the computer,the using software in the computer is as same as arduino uno.

Board PC
Vcc========== 5V DC
Gnd========== Gnd
RXD==========TXD
TXD==========RXD"

I am guessing you should connect the DTR lead from the FTDI Programmer to the DTR lead of the ST1149 board.
Check the PDF.