First edits made like in the video.

packages/react-app/src/config.js

@@ -0,0 +1,10 @@
+import { Goerli } from "@usedapp/core";
+
+export const ROUTER_ADDRESS = "[YOUR ADDRESS HERE]"; 
+
+export const DAPP_CONFIG = {
+  readOnlyChainId: Goerli.chainId,
+  readOnlyUrls: {
+    [Goerli.chainId]: "[YOUR URL HERE]",
+  },
+};