DY, unless they had a specific financial agreement, then there is nothing she can do, and nothing she can say. She did her job and that was the mitzvah of making the shidduch. It is well known that the shadchan has to get paid, that is the job of the parents or couple. A shadchan cannot force someone to pay her especially if she is NOT a professional. This is NOT a business she runs. If it were, she would know to make a contract and agree on terms before. It doesn’t sound like that is the case here. If you do it l’shem mitzvah then you did your job and thats it. Then it is up to the Baa’elei Simcha to do their job because as I mentioned earlier there can be very devastating consequences.
You don’t do a mitzvah and then “tell” someone they have to pay you for it. And you don’t do a job for anyone, if you are working for them, without telling them how much you expect or you will charge beforehand. So if it was l’shem mitzvah she did her job and the payment is up to the families involved. If she is a professional shadchan then she is NOT supposed to work until the financials are discussed and agreed upon. If you are NOT a professional you can’t “CHARGE” a fee after the fact.
So NO DY, I wouldn’t say the same for a loan or compensation for a worker because it doesn’t fall into the same category. There is a loan contract and when you hire someone to do a job you agree to pay them with the amount clear and upfront. The OP did NOT say she was HIRED, nor that she was a PROFESSIONAL shadchan who runs this business and counts on the money for parnassah.