If you choose not to use your Aslan card, nothing changes, you’ll be paid your full salary as usual on payday.
The ODP balance you see in the app simply reflects a portion of the earnings you've made so far in the pay period. It’s there if you want to use it. But if you don’t, no problem, your pay is processed exactly the same way it always has been.
Only the money you actually spend using Aslan is reflected in your payslip.