I think it was St Francis de Sales who said that when an elephant comes into the room you don’t fail to notice it. When we sin mortally, it’s apparent to a Christian with a well-formed conscience.
If purity of heart is our goal in the service of the Lord, we need to guard our senses especially when using technology.
Objectively the sin would lie in the decision to install the app and your intention behind that but God’s grace came to your aid and you reversed your initial decision. For this you should thank God.
If you examine your conscience and you feel unsettled, go to Confession before you next receive Holy Communion and confess what you’ve done. Pray for wisdom and the grace of purity of heart.
It would also help to do some study from the Catechism on the difference between venial and mortal sins. It’s not rocket science and it should be something a Christian - with the help of God’s grace - should be able to work out without too much trouble.
The Lord has called us to live in peace and to enjoy the freedom of the sons of God. I pray God’s peace for you and freedom in his service.