The definition of Royalty free as this site defines it is in the Terms. You should carefully read section 21, especially 21.4. If you mark something as Royalty Free, and sell or give it away with that license, you grant the recipient/purchaser with the rights listed there, assuming they do not violate the rights of the copyright holder as listed in 21.1 thru 21.3 So yes, you can do pretty much anything within those paramaters. Including sell it as incorporated product commercially, render it, make videos of it. etc.
As well I know CC is a collection. Its up to you to pick Which CC license you want to use. And mark your items as using them clearly by setting your item to "Custom" license and putting in which license you are using. As it is now some of your items have two drastically different licenses listed and it's confusing. Royalty Free and CC-By 4.0 are very different.
In Any event, I was just giving you a friendly heads-up. Feel free to disregard.