"We couldn't create a new partition or locate an existing one"

If you are using a USB3 stick try using a USB2 stick. That might be the problem.

Are you trying to install to a blank drive, or a drive with partitions already on it?

Is the USB stick formated in FAT32 ?

First questions, does the laptop have a legacy BIOS or UEFI, and is your USB setup to boot both legacy BIOS and UEFI?

At the point in Windows setup where you have the list of drives and partitions, press Shift - F10 to open a command prompt. Assuming the laptop has only 1 HDD/SSD, that is the HDD/SSD you are trying to install Windows onto, and there is no data on that HDD/SDD you want to keep, run the following commands:

Diskpart
Select Disk 0
Detail DIsk

Do both Current read-only state: and Read-only: say no?

Clean - this will erase the entire HDD/SDD
List Part - Are any partitions shown left on the disk? The answer should be no partitions shown.
Convert GPT - Use this command only if the laptop is UEFI
Convert MBR - Use this command only if the laptop is legacy BIOS
Exit
Exit

If the above completes successfully, Read-only states are NO, and there are no partitions on the HDD/SDD, then the problem is with the Windows 10 USB flash drive.

Then click the refresh button below the list of drives and partitions, select the unallocated space on the Drive 0 and click next to install Windows to the blank space.

GuyInDogSuit said:

That's what I thought it might be, but I used a 2.0 port.

The port is not the problem it is the stick itself. When the installer looks at the disks for comparability it looks at the USB3 stick as well as the destination drive and that's what triggers the warning message. It is not compatible with USB3. It's really makes no sense but that just the was MS coded it. This has happened to me before.

GuyInDogSuit said:

Rufus does not allow Win10 images to be written to FAT32.

It was created by Rufus, so yes, it is both. I tried all that with Diskpart and it still gives me the same error. This same flash drive has worked fine on other devices before, using this very same installer.

Your two statements inside the same post contradict each other. In order to be compatible with UEFI, the USB flash drive must be formatted as FAT32. See the Important box in step 9 here:
Create a Bootable USB Flash Drive

Did all of the diskpart commands complete successfully while in the command prompt window?

Rufus is loaded with options that when not select exactly correctly will cause problems. I use the above linked procedure to create Windows 10 USB flash drives, using FAT32 as stated in the Important box. Then for step 12 mount the Windows 10 ISO file downloaded from Microsoft and copy the files and folders from the mounted ISO file to the USB flash drive.

As final step, I like to copy the boot.wim file from \Sources on Kyhi's recovery tools ISO file to the \Sources folder of the Windows 10 USB flash drive. That way I can use all the utilities on his recovery tools drive and install Windows 10 from the same USB flash drive.