Uploading the ZIP file containing the ISO file is supported, but I recommend extracting the ZIP file first and then uploading only the ISO file into the remix tool. If that doesn't help, the NOD CD download is called "DOSCNC_Nod.zip" containing the file "DOSCNC_Nod.iso". Double-check whether that's the case and report back whether you got it solved or whether we have to dig deeper. Thanks!
Viewing post in Command & Conquer for Atari ST comments
Interesting, the message means that a very early memory allocation failed, and that should not be the case on a 4MB machine.
One of the first things the game does is to dump how much ST-RAM and TT-RAM it can allocate at max. Something like:
C&C ST - At program start:
ST-RAM 2308478 b (~2254 KiB)
TT-RAM 0 b (~0 KiB)
I'd love to know what your system is saying (you can pause the real Atari ST by pressing Ctrl+S and resume with Ctrl+Q).