Graph Paper Press Themes – HELP!

I checked with my host and I have all of the host requirements for running graph paper press themes – https://graphpaperpress.com/faq/basics/ – but the themes I’ve downloaded from them are not working. I can install them, but they show up as white boxes with a little blue box in the middle that has a little question mark inside. When I try to preview i cannot see the theme and instead see bits of the theme that look wrong.

Please help! Any suggestions welcome.