Shiftcontroller API in Power Automate

Where 123 is just the ID of the layer. In other words, you would have to clamp the IDs behind them when shifts change. The same applies to deleting layers. Now I've been looking for some approaches on oogle and I'm not really getting any smarter because I can't get the connection via the http action in Power Automate. In the tests, the flow works for ages and reports errors after about half an hour. The error is that access was denied. I tried to enter the API key somewhere but without success. Can somebody help me?

https://www.shiftcontroller.com/rest-api/