I can’t find app store on my device

The exact location of the setting in Screen Time that is preventing it is at Settings > Screen Time > Content & Privacy Restrictions > iTunes & App Store Purchases. There you will find the setting for installing and deleting apps. Just change them to allow and you can continue to use Screen Time.

Sounds like you have Screen Time restrictions that are preventing you from installing or deleting apps. Turn off Screen Time at Settings > ScreenTime, and scroll to the bottom until you find Turn Off Screen Time.