Royalties for urban simulations & visualizations for client

After reading the FAQ, the EULA and some posts on the forum I’m still not sure if we need to pay royalties or not.

We are a company that uses UE4 to create simulations (videos, pictures, VR experiences) of urban environments, which we sell to local governments and architectural companies. They will only use these simulations to inform and/or promote their projects, by social media or other means.

Is this recognized as ‘work-for-hire’ - or are we required to pay royalties?

On the work-for-hire question, is this unique work each for a single client?

Yes, each work would be unique (but multiple videos / images would be created for these projects, for the same client)

Your work for hire fees in that case would be royalty free