Insufficient space issues while attempting to install Sonoma via OCLP. Help needed

I have a older iMac 27in 2016 running El Capitan. Attempting to upgrade so this thing is usable again, but when I select "Download macOS Installer" then click Download I keep getting "Insufficient Space". It wants to download Sonoma to the SSD but there isn't enough available space. Is there a way to Download Sonoma via OpenCore to my 1T HDD or the 3.0 64GB USB that I have available? Please help thanks