Are you able to forward a simple halachic loan document at your earliest convenience ? No interest
My assumption is that you want what is called a heter iska, which is an agreement between the two sides that the lender is not really “lending”: the money to the borrower, but investing his money with him, and the “interest” is really the profit from what is now going to be an joint investment. Additionally the lender essentially has liability if the investment goes sour, except that the borrower will have to prove it in a way that would be very hard for him to do so. It is important to read the document beforehand so that both sides understand it’s ramifications..
Here is link to the Heter Iska https://dinonline.org/2018/08/21/heter-iska-6/