Most dieline templates require Adobe Illustrator to edit and add designs to. However, if you do not have access to Adobe Illustrator, you can consider using Canva Pro to add designs to a dieline template.
Canva Pro is a more economical alternative to Illustrator and has many other uses, making it a software you may already subscribe to. Do note that the free version of Canva will not be sufficient for adding dieline designs and formatting them correctly for production. Therefore, to use this alternative method, you will have to use Canva Pro.
Another option could be to use Figma for dieline design. But ultimately, Adobe Illustrator would be the best tool to use.