How to show single category archive

I have created the category.php template file for my wordpress custom theme. I put inside it the loop and the markup needed to disply my single category layout. I’m facing the issue that if the url is pointing to one particular category example: category/mycategory/ , I get a blank page with the header and footer only, the posts that are under that category are not listed as I was expecting. I’ve assigned to the categories a custom post type, but I think this is not important because it’s registered under the default categorytaxonomy of wordpress. Maybe I need another template for this, how I can fix this? It Will be possible to avoid creating new templates files and get all the content using Vue.js and the REST API?