Boot Camp The startup disk does not have enough space to be partitioned

What you see is Free Space within the APFS Container. This is not the same as space that can be made available to a Windows partition.

To check the minimum size macOS can have, post the output of

diskutil apfs resizeContainer disk0s2 limits

from macOS Terminal.

Can you post the output of

sudo fsck_apfs -n -l /dev/rdisk1

This looks clean. Use Disk Utility and try to create a FAT partition (not an APFS volume) of the size you want Windows to be. Expand the Details section and post the output. See Partition a physical disk in Disk Utility on Mac - Apple Support for reference.

You don't have enough space. There is only ine thing to do, create more space. I recommend at least 256GB for the Boot Camp partition.

maeyoshi wrote:

No, I just want to install Windows 10.

Sorry, I did not understand. I assumed you would want to install some Windows programs, create data, or perform some other Windows tasks. You also need room for swap memory and temp files.

maeyoshi wrote:

BCA says "You must have at least 42 GB of free space available."

So, 76GB should be enough.

Are you not planning on doing anything with Windows other than installing it?

Please post back, if you run into any issues.