When you reach points required to get a reward (a reward can be e.g. a credit limit increase), you will get a choice to accept the reward.
The reward displayed in the app is subject to final eligibility checks - but if you are up to date with repayments and have been following Grow guidance, you should be just fine and be offered the reward.
If you decline the reward (e.g. credit limit increase), you will still move on to the next level and start building your points towards the next reward.
But a declined reward is lost forever and cannot be accepted once you moved to the next level.