Unfortunately, there is no standard procedure for doing this on any WWW hosting provider. What is more, it may not be even possible on nginx servers shared for multiple WWW accounts. I don’t have any experience with SiteGround, and quick search for “nginx config/configuration” in their knowledge base didn’t show anything relevant. I think you’d have to ask their support if it’s possible and how to change nginx configuration.
From what I see, SiteGround offers Apache hosting as well. Would it be possible for you to switch the hosting to Apache? It seems to support .htaccess files, so Shapespark bundles should work out of the box then.