Using upload options not working as documented

The template is this:

  <form>
    <div class="file-field md-form">
      <div mdbBtn color="primary" size="sm" class="waves-light" mdbWavesEffect>
        <span>Choose file</span>
        <input type="file" mdbFileSelect [options]="options" (uploadOutput)="onUploadOutput($event)" [uploadInput]="uploadInput">
      </div>
      <div class="file-path-wrapper">
        <input class="file-path" type="text" placeholder="Upload your file" [value]="showFiles()">
      </div>
    </div>
    <button mdbBtn color="primary" (click)="startUpload()">Start uploading</button>
  </form>

The component is this

import { Component, EventEmitter } from '@angular/core';
import { UploadFile, UploadInput, UploadOutput } from 'ng-uikit-pro-standard';
import { humanizeBytes } from 'ng-uikit-pro-standard';

@Component({
selector: 'file-input-example',
templateUrl: 'file-input.html',
})

export class FileInputComponent  {
  formData: FormData;
  files: UploadFile[];
  uploadInput: EventEmitter<UploadInput>;
  humanizeBytes: Function;
  dragOver: boolean;

  constructor() {
      this.files = [];
      this.uploadInput = new EventEmitter<UploadInput>();
      this.humanizeBytes = humanizeBytes;

    this.options = {
              concurrency: 25,
  maxUploads: 25,
  allowedContentTypes: ['image/jpeg']
    };  
  }

  showFiles() {
      let files = '';
      for (let i = 0; i < this.files.length; i ++) {
        files += this.files[i].name;
         if (!(this.files.length - 1 === i)) {
           files += ',';
        }
      }
      return files;
   }

  startUpload(): void {
    console.log('starting upload');
  }

  cancelUpload(id: string): void {
      this.uploadInput.emit({ type: 'cancel', id: id });
  }

  onUploadOutput(output: UploadOutput | any): void {

      if (output.type === 'allAddedToQueue') {
      } else if (output.type === 'addedToQueue') {
        this.files.push(output.file); // add file to array when added
      } else if (output.type === 'uploading') {
        // update current data in files array for uploading file
        const index = this.files.findIndex(file => file.id === output.file.id);
        this.files[index] = output.file;
      } else if (output.type === 'removed') {
        // remove file from array when removed
        this.files = this.files.filter((file: UploadFile) => file !== output.file);
      } else if (output.type === 'dragOver') {
        this.dragOver = true;
      } else if (output.type === 'dragOut') {
      } else if (output.type === 'drop') {
        this.dragOver = false;
      }
      this.showFiles();
  }
}