To sign in, use your existing MySonicWall account. To create a free MySonicWall account click "Register".
Recently purchased license won't sync to appliance from Mysonicwall. Device TZ400
The license will download on its own. However, it should take more than a day, and probably shouldn't take that long either.
Go to your mysonicwall account and pull up the licenses for your device. If it is not there, then it won't download. Contact the seller and ask them if there are any issues with the purchase, has it been properly submitted, etc.
On your firewall's license page, you can resync your licenses by entering your mysonicwall.com credentials. Should that fail, make sure the firewall is communicating properly. Run the Check Network Settings Tool. (KB Article: How To use the "Check Network Settings" tool) This will tell you if firewall can successfully "call home." You will see License Server in the list.
Should that fail, you can reset the trust on the firewall (KB Article: Licenses not synchronized with MySonicWall - resetting the trust).
If you have issues getting through these steps or you go through all of them and it still doesn't work, pick up the phone and call tech support.