われわれは気づかない間にしばしば宣伝に影響を受けているということが強調されるべきである。

English Translation

It should be stressed that we are often influenced by advertising without being aware of it.

This sounds super robotic translation. I would translate:

人は無意識のうちに広告に影響を受けやすい点に留意すべきだ。(ひとはむいしきのうちにこうこくにえいきょうをうけやすいてんにりゅういすべきだ)

Translating “we” as 我々(われわれ)is very awkward. “We” means “people in general”, so 人は is a great term to describe the general tendency of human beings.

~ということが強調されるべきである is also super unnatural. A word-for-word translation doesn’t work. 留意する basically means “we pay closer attention to” or “we keep in mind that”, so it also means “it should be stressed (to make people aware that)”.