Is there a sin upon me for placing signs that read "I seek forgiveness from Allah and repent to Him" in public places without permission?

There is no harm in placing plaques and posters that bear remembrances (adhkar) and reminders of Allah and good deeds in respectable places that are not exposed to disrespect, as this falls under the category of reminding, calling to good, and pointing it out, due to the saying of the Messenger of Allah, peace and blessings be upon him: "Whoever guides to good is like the one who does it." And if placing them in a private place requires permission, then permission must be sought from its owners.