I wantto place my pictures with the module UIkit 3 Gallery in a article on my website. Is it not possible to assign a map at once, or do I have to place every image piece-by-piece?

These are Joomla Basics. You can view each module in the post. For this you use either loadposition or loadmoduleid.
docs.joomla.org/How_do_you_put_a_module_inside_an_article%3F