Signed up an account with ”hide my email”

I have a problem i have been trying to solve for a while so now i’m reaching out to you guys. I signed up on a trading app with my Apple id and the hide my email function. I’ve put in some money on this app and there was no problem. But now when i need to get the money out of there, they say that i have to contact them from my email account that’s linked with the app account. Does anyone have any idea on how to fix this?