You can definitely transfer more than US$500 at once. If you have people you can work with in the destination country, Bank of China can send thru MoneyGram which is a lot less than wire transfer US$14-21 -ish depending on how much you’re sending.
I was thinking to try PayPal bc convenience and I thought fees might be comparable to MoneyGram but I haven’t gotten it set up yet - is it worth it?
I wasn't able to get mine to work either and finally asked at the bank lobby desk - a very persistent helper there figured out that I needed to have the bank add my phone number to my account. after that it worked without a problem. Not sure if yours is the same problem, but it's worth a try.