Royalties for work-for-hire services

I’m a freelancer consider to use the engine to provide work-for-hire services for various clients. The work is related to visualizations for new products and architectures which can be displayed in a commercial environment such as sale offices for new house promotion or new product enouncement. I will offer my work as a development and receive a fee.

I would like to know if my clients and I need to pay any royalty fee. Thank you

There is no royalty on work-for-hire fees which represent custom work for a single client. It sounds like that addresses your fees.

If the resulting product is not directly sold or monetized, there is no royalty on that either.