Macbook Pro with Mavericks Help Please

Macbook Pro 2012 , 2.5 Intel i5, 4GB

The Macbook has used recovery to erase disc and install Mavericks.

Just wondering what the next step is to be able to use OpenCore as I understand I have to upgrade to at least Big Sur (osx 11<) to use the patcher.

I tried downloading the image but it failed when I tried to instal.

Would I need to create a bootable disc drive and instal it via that method instead of through Mavericks?

A bit new to this but am ok with tinkering.

Thanks