I don't know what you are trying to install but that's not how it usually works. After booting from usb and some basic setup like language, keyboard, network, it should take you to disk partitioning unless you have chosen to use existing partitions to install. If there is no option to get to disk partitioning then maybe there is a problem with your bootable linux usb. Try different one. Also bootable linux usbs usually allow you to try live system without installing and they also include tools that can be used for partitioning, so you can try that too.