Google ad manager and react

I have a customer that has a small digital newspaper where they replaced their google ad manager account with their new owners. They created all the campaigns in the new account and I changed the network ID but they ads are not showing up.

The site's framework is MEARN and basically, everything is in react js. I know I only need to replace the old hierarchy with the new simple one. Before, the structure was newspapername/home/block and now is newspapername/block because they were using a premium account and now, they are using a free account. I can't find out where to change that in the code because I'm not a react developer.