Redirecting an Ember application to an omniauth authorize URL

I need to send the user of my application to the coinbase authorization page. My application uses an Ember.js front end and is connected to a Ruby on Rails back end. I have been able to execute this functionality using rails views before, but I am having trouble doing so using an external client. Client side, I have constructed an adapter which runs the requisite server side functions to generate an authorize. When I click the button which fires this adapter and I am returned a correct redirect url, but my app throws a 404. I am fairly certain I need to use the method window.location.replace(redirect_url) to launch this redirect, but I cannot seem to figure out the syntax for properly returning the value and plugging it into this call.

the method called in the route:

donate (params) {
      return this.get('store').findAll('account', {reload:true})
        .then((accounts) => {
          return accounts.findBy('editable', true);
        })
        .then((account) => {
          params.patronId = account.id;
          const adapter = this.store.adapterFor('account');
          // adapter.donate(params);
          return adapter.recieve_donation(params);
        })
        // .then(() => this.transitionTo('accounts.search-accounts'))
        .then(() => {
          this.get('flashMessages')
          .success('We have successfully sent your donation');
        });
    },

the adapter method:

recieve_donation(params){
    console.log(params);
    const api = this.get('host');
    const url = `${api}/auth/coinbase`;
    // , {data: params}
    return this.ajax(url, 'GET');
  },

I also am not sure if the problem is on my server side; my intuition says the fact that I am successfully returning a url leads me to believe it is not, but I can't be sure.

How can I redirect my ember app to the returned redirect URL?