Thanks for the question.
Catholics are not obliged to believe any private revelation. Even Church approved apparitions like Fatima or Guadalupe do not require assent like official Magisterial teaching.
That being said, apparitions like Fatima are worthy of belief and shouldn't be dismissed so easily. In that particular case a spectacular miracle, viewed by believers and non believers, took place to confirm the validity of the messages.
In most cases the local bishop is responsible for approving the content of messages to insure consistency with the Gospel. Sometimes others are published without having ever been scrutinized so, you have to take any private Revelation very cautiously and skeptically.
Still, when there are many different sources that seem to converge on particular themes or warnings, it is worth paying attention.
But above all we must be prepared to meet the Lord at any time, and certainly during these unusually dark times we should be extra alert to the signs of the times and make sure our spiritual house is in order.