Google used to do very little curation of the Play Store (or Android Market, if you go back far enough), but it has long ...

Google plans to start blocking users from sideloading unverified apps, in an attempt to improve the security of Android.

Unfortunately, iPhone users cannot do this, as Apple does not allow side-loading apps. However, for Android users, this means there is now a safe and official method to download TikTok once more.