The first parameter is the struct definition, the second parameter is an instance of that struct.
Assuming your data table is storing structs of type SRClientInfo, it should look like this :
FString Row;
// Get a pointer to the struct instance pointed by the row.
// The string parameter here is only used for providing context when logging errors/warnings. It's not useful otherwise.
// We use void* generic pointer because we don't know the type at compile time, since it is passed at runtime.
void* StructPtr = ST.GetRow<UScriptStruct>(TEXT("foobar"));
// Convert our struct instance to json, using the USTR struct schema.
FJsonObjectConverter::UStructToJsonObjectString(USTR, StructPtr, Row, 0, 0, 0);
UE_LOG(LogTemp, Warning, TEXT("%s"), *Row);