Your questions about SoFi Hong Kong are answered here

If you haven’t traded recently, you can make a withdrawal whenever your ‘Cash Balance’ is positive.

If you make a sell trade from the HK market, it’ll take 2 business days (T+2) to settle. While if you make a sell trade from the US market, it’ll take 1 business day (T+1) to settle. This amount will be shown as ‘Net Unsettled’ on the ‘Account’ page in the app (Menu -> Account -> Downward arrow under ‘Account Value’).

On the third business day (T+3) for sell trades in the Hong Kong market and on the second business day (T+2) for sell trades in the US market, you will be able to see it as ‘Cash Balance’ and you can submit a withdrawal request to transfer funds back into your registered bank account. Cut-off times and transfer processing time apply for fund withdrawals.

Please note that if you execute more trades within the (T+3) period after you make the first sell trade, the unsettled balance maybe accumulated.