The key thing to remember is that revenue based finance is not a loan, so don't use any terminology that would suggest this is a loan.

Don't Use	Use Instead
Loan, lending	Fund, funding
APR, interest rate	Fee, fixed fee
Repayment, repay, pay back	Payments, pay
Repay as you earn	Pay as you get paid
Loan, credit agreement	Revenue based finance agreement, purchase agreement
Loan, amount borrowed	Advance, advance amount
Lender	Funding provider, finance provider
Borrower	Customer, business, merchant
More credit	Renewal, further advance
Term	Estimated payback period

Note that the business cash advance is considered a loan in Germany, so the terminology you'll use in Germany will differ.