Firefox Android: "Add-on is not supported"

Question

I'm creating a private add-on for Firefox on Android. I can successfully launch the add-on using wex-ext run and use it, but it does not stay if Firefox is restarted.

I have also created a zip file of the add-on and uploaded it to AMO as an unlisted add-on. After a few minutes the add-on gets signed and coverted to .xpi. I click the link to the xpi in Firefox on Android, the Add-ons screen opens and then Firefox says "Add-on is not supported" in a toast-like notification.

What am I doing wrong?

manifest.json:

{
  "manifest_version": 2,
  "name": "NAME",
  "version": "1.0.2",
  "description": "Custom Firefox Extension",
  "permissions": ["activeTab", "storage", "webNavigation", "*://url.com/**"],
  "content_scripts": [
    {
      "matches": ["*://url.com/"],
      "js": ["content.js"],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "113.0"
    },
    "gecko_android": {
      "strict_min_version": "113.0"
    }
  }
}

The add-on installs fine if I click the xpi link on my computer.