All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Ticking the box of "I have read the agreement" without the person having actually read the conditions is telling something which is not actually the reality, and hence, is considered a lie. The Prophet, sallallaahu ‘alayhi wa sallam, told us that telling lies is a way to Hell. He said: "Lying leads to wickedness and wickedness leads to Hell. A man persists in telling lies until he is recorded as a liar in the sight of Allaah." [Al-Bukhari and Muslim (This is the wording of Al-Bukhari)] ‘Aa’ishah said: "The most hated manner to the Prophet, sallallaahu ‘alayhi wa sallam, was lying. When he learned that a person has told a lie, he would remain grieved until that person repented of it." [Ahmad and At-Tirmithi]
The fact that the conditions are long does not justify lying, so the Muslim should take precaution in his religious matters to become assured. Al-Hasan ibn ‘Ali said: "I memorize from the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, the following statement, 'Give up what is doubtful to you for that which is not doubtful; for truth is peace of mind and falsehood is doubt". [Ahmad and At-Tirmithi]
However, the exception to that ruling is when a person has read this agreement previously or someone has told him about it or he knows that it is not different from what he has read before or if ticking the box of agreement does not necessarily imply that the user has read the agreement, but rather that he just accepts the conditions whatever they are. In all these cases, the user is not considered a liar.
Allaah Knows best.