If you click the "X" on the right to dismiss this tip, it won't come back again. Or, if you ever use the Repeat Grid feature even one time, that should also stop the tip from popping up.
If you've done one of those things and it's still appearing, please let us know -- there may be something wrong with folder permissions that's preventing XD from saving preferences info in that case.
I closed this popup and used Repeat Grid not once. But sometimes this hint is up again.