Windows 7 is not supported on ANY machine past skylake.

https://www.dell.com/support/article/us/en/04/how11804/how-to-install-windows-7-on-systems-with-skylake-chipset?lang=en

Microsoft, Intel, AMD, etc stopped supporting 32 bit software as well as windows XP/VISTA/7/8 etc on new hardware.

Class 3 Bios is 64 bit only, and DOES NOT HAVE CSM so secure boot is Always.

There is no help for you.   Windows 7 is End of Life in Jan 2020.

OEM partners are supporting Windows 7 on Skylake machines or earlier until the end of Windows 7's "extended support," which happens on Jan. 14, 2020.

Intel Skylake processors, also known as "Intel Core sixth-generation products,"

7th, 8th, 9th GEN processors ONLY support windows 10.

7th Gen Intel Core (Kaby Lake) processor family and AMD's 7th generation processors (e.g. Bristol Ridge) will only be supported on Windows 10, and all future silicon releases will require the latest release of Windows 10.