A new app needs installing on a phone that's already set up with Brickify. Here's the full loop — unbrick, install, decide where it's blocked, re-brick.
This is the general version of the loop — for a specific worked example (block a new app on weekdays, free it up on weekends), see Add a new app and allow it only on weekends once you've finished here.
Open Brickify and tap Unbrick (or Stop Brickify → if nothing's actively blocking right now), then enter the PIN and second factor if one's set up. This is needed because the App Store or Play Store is commonly one of the apps a profile blocks.
Play Store (Android) or App Store (iOS) — search for it and install as normal.
Android: the app needs to actually be installed before it shows up in Brickify's block-list picker. iOS: Family Controls' picker works from Apple's whole catalog rather than what's installed on the phone, so it can technically be pre-blocked before installing — but installing first keeps the steps the same on both platforms.
Setup → Profiles. Block lists are set per-profile, not globally — open each profile where you want this app blocked and turn it on there; leave it off in any profile where it should be allowed (e.g. a Weekend profile).
Android: find it in the searchable app list and toggle it on. iOS: tap Choose apps to block → (or Change apps to block →) and reselect via Apple's picker, including the new app alongside whatever's already chosen.
Tap Start Brickify on the Home tab if it isn't already running — one tap, no PIN needed.
Remember: there's no single master block list. A new app has to be added separately to every profile you want it blocked on — a "School Day" profile and a "Weeknight" profile each need their own toggle flipped.
On Android, you'll also get a notification and an email (if you've added your address in Setup) whenever a new app is installed — a useful safety net, but it doesn't add the app to any block list for you; step 3 above is still needed. iOS can't detect new installs at all, which is exactly why blocking the App Store itself is worth keeping on any profile you want to hold firm.