My main website is the root, and the other websites have a folder to upload the files.
What happens is that I try to upload Grav to the root, but it returns me a blank page when I browse the domain I uploaded Grav to. Can you help me?
This is a bit tricky because running sites inside other sites is potentially problematic. This is because CMS platforms such as Grav and even Joomla/WordPress, etc use an .htaccess file to route requests to a index.php of the CMS. This allows for SEO URLs.
If you try to put one site inside another, the parent site might try to route the path of your child site as a URL to a page it knows about.
So back to the original issue, Grav displaying white page. I would check first that your running PHP 5.4+. If sill a white page, then something is causing PHP to throw an error. You will need to find what that error is either by a) looking in the error log or b) turn on PHP errors: https://my.bluehost.com/cgi/help/109
You might need to contact your host and ask them directly as I’m not familiar with how they setup their hosting.