Override the default route given by Payola Engine. I setup my routes like this. It's working on Rails 5.2.
scope module: 'payola' do
mount StripeEvent::Engine => 'payola/events', as: :payola
post 'payola/buy/:product_class/:permalink' => 'transactions#create', as: :buy
get 'payola/confirm/:guid' => 'transactions#show', as: :confirm
get 'payola/status/:guid' => 'transactions#status', as: :status
post 'payola/subscribe/:plan_class/:plan_id' => 'subscriptions#create', as: :subscribe
get 'payola/confirm_subscription/:guid' => 'subscriptions#show', as: :confirm_subscription
get 'payola/subscription_status/:guid' => 'subscriptions#status', as: :subscription_status
delete 'payola/cancel_subscription/:guid' => 'subscriptions#destroy', as: :cancel_subscription
post 'payola/change_plan/:guid' => 'subscriptions#change_plan', as: :change_subscription_plan
post 'payola/change_quantity/:guid' => 'subscriptions#change_quantity', as: :change_subscription_quantity
post 'payola/update_card/:guid' => 'subscriptions#update_card', as: :update_card
post 'payola/update_customer/:id' => 'customers#update', as: :update_customer
post 'payola/create_card/:customer_id' => 'cards#create', as: :create_card
delete 'payola/destroy_card/:id/:customer_id' => 'cards#destroy', as: :destroy_card
end
Lastly, deactivate disable_with, which is on by default with Rails 5.0+, I believe. It will stop the JS form code that Payola uses to process payments.
<%= f.submit "Submit" data: {disable_with: false} %>