If this is a 'work' computer, meaning owned by your employer, have you received permission to do this? If not, wouldn't it be simpler to just install Ubuntu on a flash drive and being it with you?
Windows 10, pre-installed? If so, it is UEFI and Ubuntu must be UEFI. See the link below.
https://help.ubuntu.com/community/UEFI
Is windows 10 hibernated? You would need that off as well as fast boot and anything related or the partitions won't be mounted or shown.
Does running fdisk display the partitions?
Which option are you selecting for the Installation Type? You should use the manual "Something Else" option.