Base64 encode not working

Hello,

I want to ask why my base64 encode not working while encode string ?
This is my code :

let mddd : string = "f3e0323006e15ee8a8673d696fac4a95";
    let timespan = moment().unix()
    console.log("Timespan : ", timespan);
    let uuid_ = UUID.UUID();
    console.log("nonce : ", uuid_);
    let data = JSON.stringify({"customerId": "c54321", "name": "Rezkar", "customerType": "premium", "level": 1})
    let testmd5 = Md5.hashStr(data).toString();
    console.log("SHA256 : ", testmd5);
    this.base64.encodeFile(mddd).then((base64File: string) => {
      console.log("Here")
      console.log(base64File);
    }, (err) => {
      console.log(err);
    });

And this is the result :

Please help me, thank you