Jira creating Test repository for Product

Hi I'm new in Jira and want to create a Test repository for one product without using any add-on.

This test repo will include all generic test cases and custom ones for each customer. I wont execute them in Jira but will use Jira to keep test details(test steps, pre-post conditions, result etc.) My goal is to create Parent issue/folder for main Product on top and under that there will be sub folders/items like Generic-Tests, Customer1 , Customer2 etc. that includes related tests in each.

At first was planning to create Epic and under that some sub items but not looks fine, so now stuck.

Do you have any solution in order to create that type of test repo in Jira?