A variety of users have reported that they get an error message about failing to meet UEFI settings even though they are attempting standalone install which does not require UEFI.
This is an indication of one of money pre-existing install issues with the machine or USB you're using - the irrelevant error is just a result of our software triggering the wrong error code.
Some things to try/consider if this happens to you:
1) Many users have had success by first formatting their HDD/SSD before running the install.
2) A few users have had success by simply using a few different USB sticks - this seems to revolvearound the fact that certain USB sticks aren't fully recognized as removable by the OS. If you have this issue, beg/borrow/steal other USB 2.0 sticks of several different brands to try install from.
3) Often this issue (and many other issues!) are more to do with the UI-wrapper around installation than they are an issue with installing in and of itself. That's why we recommend you roll up your sleeves and try a manual, cmd line install.