Thank you so much! The second option worked smoothly.
I still cannot assign a standard template from the “extandable” theme.
Here is a video of a German version: https://drive.google.com/file/d/1k5evKpKyhQPPH0M4_XHUmC5b_yJvn3RA/view?usp=sharing
At the end I move back to the template settings and switch to “standard” templates but can only select “Seiten” – No other template out of the theme can be selected. I gues I am missunderstanding something. Thank you for the hint, it works now for me and I can move forward with the project. The template question will probably come up in 2 weeks again.
