Account lost

My little Brother has been playing and grinding on fc mobile for 3 years now. Today he accidentally deleted the game from the device and he cannot get his account back. I remember signing in his account with Google play, but as I sign in with Google play now, it should've shown me a text smth like "we have found an existing account" or some shi but it did not happen in his case. Please help, he's afraid he may lose his progress...