on page of Assemble the Car — SunFounder 3in1 Kit documentation, steps of 6 and 7 the standoff should be M3x10mm. you can’t find M3x10mm standoff.
For step 6B of the assembly, you are using M3x6mm screws and M3x10mm standoffs.
For step 7A of the assembly, you are using M2.5x6mm screws and M2.5x11mm standoffs.
Can you please describe in more detail what your specific question or issue is?
Are you having trouble with the assembly using these parts? Or are you missing some of the required components?
Please provide more details about the problem you’re facing, and I’ll do my best to help you resolve it.