No data available in consent report

Even if I did the Cookiebot integration according to: Cookiebot integration | Piwik PRO help center.
I cannot see any data on consent tab in the reports section. When I load the website, the consent text pops out but no data in consent report. why?

Hi,
First of all, welcome to the community! We are glad to have you here.
Could you please share a URL of the website that you are referring to?

Hi, thank you! here’s the url: https://www.marketinganalytics.de/

Could you please check if there is a tracking code container missing on your page? I can’t seem to find it anywhere in your source code.
Here is an article on that: Install a container (with a tracking code) | Piwik PRO help center

Actually I’m using GTM. Does it make a difference about the problem?