If you don't receive mana or can't send it, please reinstall the application in Facebook and disable all blocking add-ons in your browser (such as AdBlock).
For reinstalling the app you need to follow these steps:
1. Open the app
2. Copy the link in the browser's address bar (Ctrl+C)
3. Go to the Facebook account settings: Open your account menu at the top right corner of your Facebook page, then open "Settings"
4. In settings go to Apps, find Throne Rush there and click on the cross, then click "Remove"
5. Paste link in the browser's address bar (Ctrl+V) and push "Enter"
6. Click on "Play now" button.