OpenCore Legacy Patcher save downloaded installer at:
/private ▸ var ▸ folders ▸ rv ▸ gdxk_zcj547c9n7r3b7v4qzm0000gn ▸ T ▸ _MEIOPTmCs ▸ payloads
You can access it by clicking Go > Go to Folder menu in Finder.
Then enter /private and press Enter