The download is a ZIP archive, containing all of the formats Ink/Stitch can export to. It also contains the SVG source file. You can use the free Inkscape + Ink/Stitch combo to modify the design and re-export it. If you have a larger hoop you can group more of the designs, all color sorted for minimal thread changing. If you’d like to change a snap tab to a dangle, turn something into a patch, make a die line, or resize it without affecting stitch density, you can do any of those sorts of things.
This is copyrighted by Silver Seams in the year noted in its URL, and licensed under Creative Commons’ CC-BY-SA. This basically means you’re free to sell items you make from it, provided you give reasonable attribution, and that if you modify it you’re required to share your changes with the world under the same license (the actual legal bits are in the link).
This is a fan work, not licensed or endorsed in any way, so it’s up to you to get any other permissions you need from the IP owner.