The future progressive tense is used when expressing events and action in progress at some future point, however the example sentence cannot be understood in that way.
公式問題集には"受け身の現在進行形"と説明されています。
In the official question collection it is explained as being "passive voice of the present continuous tense".
進行形の文では、動詞のing形、つまり現在分詞となります。
In a progressive tense sentence it becomes the -ing form verb, that is the present participle.
例文は過去進行形の文です。皆さんは進行形を学習するとき、どのように教わりましたか?
The example is a past progressive tense sentence. How was everybody taught when they were learning about progressive tense?