Steps to reproduce:

1. Install Android Studio 3.6.1
2. Install Andoid SDK using it
3. Open Unity
4. Set platform to Android
5. Under Unity > Preferences ... > External Tools uncheck "Android SDK Tools Installed with Unity (recommended)
6. Select the path of SDK you just installed using Android Studio 3.6.1
7. Try to Build & Run

Expected Result: Unity detects all the required tools and uses that SDK
Actual Result: Unity is trying to detect SDKMANAGER in
"/Users/${USERNAME}/Library/Android/sdk/cmdline-tools/latest/bin/sdkmanager"
when it actually is in
"/Users/${USERNAME}/Library/Android/sdk/cmdline-tools/latest/tools/bin/sdkmanager"