You should not disable UEFI support!!!! Although it may initially appear to let you make progress, setting the computer to favor BIOS/CSM/legacy-mode booting is more likely to cause additional problems than to solve problems. The reason is that mixing the existing EFI-mode Windows boot with a BIOS/CSM/legacy-mode boot of Linux ranges from impossible to awkward, depending on your computer. The most probable outcome of installing Linux in BIOS/CSM/legacy mode alongside an existing EFI-mode installation is that you'll have to play games with boot loaders after the installation, effectively undoing the BIOS/CSM/legacy-mode boot loader installation that was created by changing that firmware setting. In other words, you'll create work for yourself. Unfortunately, this bizarre path has become a popular one because people keep repeating the same advice, which involves both the use of a BIOS/CSM/legacy-mode installation followed by use of Boot Repair to fix the problems that the first bit of advice caused.
That said, you may need to disable Secure Boot, though, so go ahead and do that. Unfortunately, the details of how to do this vary from one computer to another.
I recommend you read the following pages for help:
If you continue to have problems after following the advice on those pages, post back with details of what's happening.
