Hey @alisaruss, welcome to the Community.
Hope you're doing great!
If your address doesn't autocomplete, you might still be able to find it if you enter it manually and select ‘Find’.
If you still can’t find a specific address, try any of the following:
Note: Please don't use someone else's address.
The family members you invite should use that exact same address to join, so make sure you tell them what you entered.
I'd also suggest checking this article for more about Spotify Premium for Family.
Hope it helps :)