I have downloaded the flex installer several times and tried uploading it to the server via FTP. I have figured out that I need to add the java runtime environment into the SCRIPT not my root path (that was not clear to me before).
But now when I run the script this is what I get
analytics:/home/bluethundr# ./flexbuilder_linux_install_a4_081408.bin Preparing to install... Extracting the installation resources from the installer archive... The size of the extracted files to be installed are corrupted. Please try to download the installer again and make sure that you download using 'binary' mode. Please do not attempt to install this currently downloaded copy.