The form & portal on the Free plan are limited to internal testing to check if the extension will satisfy your requirements. Internal testing means you need to log into our website on your device to be able to preview the extensions. You don't need to have a paid plan if you're trying to test miniExtensions on mobile, you just need to be logged into your miniExtensions account on each device you want to preview your extension on. If you have multiple miniExtensions accounts, make sure you're logged in to the right account.

Once you find miniExtensions to be a good fit for your project, switch to a paid plan in your workspace settings. This will then allow you to share your extensions publicly.