Thanks a lot! For posts created by a user (author) this works perfectly, it worked also with the Elementor Post Info Widget using the Author meta with my custom fields keys.
However I still struggle with pages displaying infos about a specific user. I am half way familiar with wordpress and its templates but new to Elementor, trying hard to get the "translations" from wordpress to Elementor.
I tried to get user infos - not the post author - to build an Elementor page template, the same with an Elementor author archive, but can't figure out there when to use which meta info or metabox field. I looked also in the Elementor forum, but this didn't help either.
Any help on this is much appreciated ...