I have no knowledge of this API but reading the docs it says to use the endpoint ttps://db.ygoprodeck.com/api/v7/cardinfo.php
and pass the query string with the parameter cardset
set to the "set" you want. That would, in theory, return back all the cards in that set which is what I understand you're trying to do. They even have an example query: https://db.ygoprodeck.com/api/v7/cardinfo.php?cardset=metal%20raiders&attribute=dark
For the error you're getting back though that is different and can happen on any call. The issue appears to be that there is too much data for it to return to you. However there docs don't seem to indicate how they do paging, if they support it at all. I would recommend that you try filtering down even further first just to get valid data back. Once that works then try the full set again.
Note that for testing APIs you should consider using either curl (command line) or Postman (UI). The browser may work for simple GET requests but you are limited in what you can do with it. Many APIs ask that you set some HTTP headers when sending requests and the browser wouldn't make this easy. It is possible you need to set an HTTP header telling their server how much to return in a batch. Their docs don't talk about this so you may need to contact them about how paging works.