irb(main):118:0> test2 = Spree.user_class.first
  Spree::User Load (16.0ms)  SELECT `spree_users`.* FROM `spree_users` WHERE `spree_users`.`deleted_at` IS NULL ORDER BY `spree_users`.`id` ASC LIMIT 1
irb(main):119:0> test2
=> #<Spree::User id: 1, email: "admin@example.com", persistence_token: nil, perishable_token: nil, last_request_at: nil, login: "admin@example.com", ship_address_id: nil, bill_address_id: nil, created_at: "2020-08-25 04:14:24", updated_at: "2020-08-25 11:05:30", spree_api_key: "f9e21147d1d6951021a12a31469b0cda5392bfd7fee7c5ef", authentication_token: nil, deleted_at: nil, first_name: "admin", last_name: "admin", photo: nil, phone: "+79050000000">
irb(main):120:0>

select_users = Spree::Digital::Subscription.where(ends_at: time_range,renewal: true)
irb(main):121:0> select_users
  Spree::Digital::Subscription Load (0.6ms)  SELECT `spree_subscriptions`.* FROM `spree_subscriptions` WHERE `spree_subscriptions`.`ends_at` BETWEEN '2020-08-28 16:17:32' AND '2020-08-29 16:17:32' AND `spree_subscriptions`.`renewal` = TRUE LIMIT 11
=> #<ActiveRecord::Relation [#<Spree::Digital::Subscription id: 1, user_id: 1, subscription_plan_id: 1, starts_at: "2020-08-25 11:11:28", ends_at: "2020-08-29 16:00:00", renewal: true, created_at: "2020-08-25 11:11:28", updated_at: "2020-08-28 14:41:48">]>

irb(main):122:0> test2 = Spree.user_class.joins(:spree_subscriptions)
irb(main):123:0> test2
Traceback (most recent call last):
ActiveRecord::ConfigurationError (Can't join 'Spree::User' to association named 'spree_subscriptions'; perhaps you misspelled it?)
irb(main):124:0>