Toast without style

Expected behavior I am using the toast module:

app.module.ts

    import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';
import { RouterModule } from '@angular/router';

import { DropdownModule, MDBSpinningPreloader, MDBBootstrapModulesPro, ToastModule } from 'ng-uikit-pro-standard'

import { AppComponent } from './app.component';
import { NavMenuComponent } from './nav-menu/nav-menu.component';
import { HomeComponent } from './home/home.component';
import { ApiAuthorizationModule } from 'src/api-authorization/api-authorization.module';
import { AuthorizeGuard } from 'src/api-authorization/authorize.guard';
import { AuthorizeInterceptor } from 'src/api-authorization/authorize.interceptor';

import { CustomersAdminComponent } from './admin/customers-admin/customers-admin.component';
import { BranchesAdminComponent } from './admin/branches-admin/branches-admin.component';
import { BranchCreateComponent } from './admin/branch-create/branch-create.component';
import { BranchEditComponent } from './admin/branch-edit/branch-edit.component';
import { OrdersAdminComponent } from './admin/orders-admin/orders-admin.component';
import { OrderCreateComponent } from './admin/order-create/order-create.component';
import { OrderEditComponent } from './admin/order-edit/order-edit.component';


@NgModule({
  declarations: [
    AppComponent,
    NavMenuComponent,
    HomeComponent,
    BranchesAdminComponent,
    CustomersAdminComponent,
    BranchCreateComponent,
    BranchEditComponent,
    OrdersAdminComponent,
    OrderCreateComponent,
    OrderEditComponent
  ],
  imports: [
    BrowserModule.withServerTransition({ appId: 'ng-cli-universal' }),
    HttpClientModule,
    FormsModule,
    ReactiveFormsModule,
    ApiAuthorizationModule,
    DropdownModule.forRoot(),
    ToastModule.forRoot(),
    MDBBootstrapModulesPro.forRoot(),
    RouterModule.forRoot([
      { path: '', component: HomeComponent, pathMatch: 'full' },
      { path: 'customers-admin', component: CustomersAdminComponent, canActivate: [AuthorizeGuard] },
      { path: 'branches-admin', component: BranchesAdminComponent, canActivate: [AuthorizeGuard] },
      { path: 'branch-create', component: BranchCreateComponent, canActivate: [AuthorizeGuard] },
      { path: 'branch-edit/:id', component: BranchEditComponent, canActivate: [AuthorizeGuard] },
      { path: 'order-create', component: OrderCreateComponent, canActivate: [AuthorizeGuard] },
    ])
  ],
  providers: [
    { provide: HTTP_INTERCEPTORS, useClass: AuthorizeInterceptor, multi: true }, MDBSpinningPreloader
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

order-create.component.ts

......

constructor(public http: HttpClient, @Inject('BASE_URL') public baseUrl: string, public fb: FormBuilder, public router: Router, private toast: ToastService) { }

......

submitForm() {

    if (!this.selectedCustomer) {
      this.toast.error("Select a customer")
      return;
    }

    this.createOrder(this.myForm.value);
  }

Actual behavior The toast message is opening without style or message

Resources (screenshots, code snippets etc.)