I just purchased the Tortle as a playable race for $1.99, but they don't show up in character creation. I have all possible options / optional features/options enabled.

Most likely answers in order of probability (highest to lowest):

1. It can sometimes take a little bit for the system to update with new purchases.
2. Check here to make sure your Account Entitlements are in sync: (https://www.dndbeyond.com/account/marketplace)
3. Don’t forget that “on” is red (to the right).

If you bought it for $1.99, that was likely the monster stat block, not the race (which is $2.99.) Check the Tortle Package individual purchase options and see whether or not you got the part under Races.

Yep, this was the issue, I ended up buying the right thing! Thanks all!