usage.md

import { BrowserAnimationsModule } from '@angular/platform-browser/animations';

// RECOMMENDED import { AccordionModule } from 'ngx-bootstrap/accordion'; // or import { AccordionModule } from 'ngx-bootstrap';

@NgModule({ imports: [ BrowserAnimationsModule, AccordionModule.forRoot(), ... ] }) export class AppModule(){}

Also should be added web-animations-js polyfill for IE browser (Edge)