First time OCLP user - Problem! Grateful for advice

Just found this reddit page for OCLP while having trouble. Wondering if anyone could comment on my issue please? .......

I am running OSX 10.15.17 on a late 2013 27" imac. I've just learned about OCLP and decided to dive in, I'm following the instructions here: https://dortania.github.io/OpenCore-Legacy-Patcher/INSTALLER.html#creating-the-installer

However I hit a major problem early on. I can't download installers. When I click to download I get constant errors:

"Error - Failed to download installer Catalog from Apple"

I have a perfectly good and very fast connection. I have no firewall issues.

Grateful if someone could comment on whether this is a known issue, or worst case, just point me towards a way to grab a Venturer installer from somewhere else to bypass the issue.

thanks