I would agree that the error messages and proposed solutions you are seeing are a bit of jumble.
Error: The file C:\Users\conspai\AppData\Local\Temp\biw5zqm5\OptimizeCe_105Trans.exp could not be saved. Check that the specified file directory exists and is writeable.
Failed to schedule the following peptides with the current settings:
R.HLHFTLVK.D [34, 41] - 42 transitions
R.DYYFALAHTVR.D [50, 60] - 42 transitions
K.ARPEFTLPVHFYGR.V [192, 205] - 42 transitions
R.VLYPNDNFFEGK.E [278, 289] - 42 transitions
R.HLQIIYEINQR.F [399, 409] - 42 transitions
K.DFYELEPHK.F [470, 478] - 42 transitions
K.VFADYEEYVK.C [773, 782] - 42 transitions
Check max concurrent transitions count and optimization step count.
But, I think this final message is the one to focus on, since your command-line contains the argument "--exp-max-trans=40". That means that you are not allowing for enough transitions, since these peptides need 42. Try increasing this number to 42 or more to see if that removes these error messages.