mdb is not defined

Expected behavior I would like to use the function stepper.nextStep() (I work under VueJS) Actual behavior But when I initialize with new mdb.Stepper I get an error that mdb is not defined. Resources (screenshots, code snippets etc.)

<script>
import { ref } from "vue";
import {version} from '../../package'

export default {
  setup() {
    let externalScript = document.createElement('script')
    externalScript.setAttribute('src', 'js/mdb.min.js')
    document.head.appendChild(externalScript)
  },
  data: () => ({
appVersion: version,
inscription_form: {

}
  }),
  methods: {
connect() {
  // Je met en place le chargement
  document.getElementById("login_btn").style.display = "none";
  document.getElementById("login_loader").style.display = "block";
},
select_type(type) {
  /*
  * 1 => Restaurateur
  * 2 => Maitre d'hôtel
  */
  this.connect();
}
  },
  created() {
  },
  mounted() {
    const myStepperEl = document.getElementById('stepper');
const stepper = new mdb.Stepper(myStepperEl);
  }
};