Why does it indicate that I cannot make an advance withdrawal for home ownership, or the amount is 0 even though I have capital?

There are several possibilities for this:

1. you have already made an early withdrawal in the last 5 years?

--> If so, you have to wait until 5 years have passed before you can make a new early withdrawal.

2. your amount is less than CHF 20,000?

--> You can only make an early withdrawal if the capital is at least CHF 20,000.