yeap, what alicia said is right.
i think this is their process. When you apply for the flat, they want to make sure you have the income to potentially purchase the flat.
Meaning to say, eg. if a couple is earning $2k combined income, their HLE will approve say eg. $200k.
So they can only buy flat that cost lesser than $200k.
At the same time, it will also check the current balance of CPF is enough to pay the 10% upfront or the 5% staggered upfront where another 5% is paid during collection of keys.
the HLE in this case is not used for taking a loan from HDB yet.
By the time the flat is ready for collection, the loan will be needed. Thus you need to submit your HLE again and this time this is used for the HDB loan approval.
My guess is that this is the process.