Trying to download big sur on a old clover sierra hackintosh, download keeps being refused due to incompatibility. Any suggestions?

I'm using my old hackintosh t420 to make a bootable usb. Am I being denied the download due to my hackintosh being labeled a 2012 macbook pro? I can't seem to upgrade to anything past sierra, not high sierra or catalina.

I'm fine with my thinkpad being on sierra, that doesn't bother me. But I can't access this download and I'm unsure what to do, it's been a few years since I've kept up with the scene.

Thanks