Open group entry to everyone?

no

Nope, but you can delete the giveaway. :P

Nope, unless you included the whitelist when you made it and then you can add people.

Okay, cheers for quick answer

Possible solutions:

1. Delete the giveaway
2. Invite more people to the group just so they can enter the giveaway
3. Make the group public
4. Do nothing

Once You create one, it is only possible to change description xD

Fair enough. Did not realise this. Cheers

make it a group/whitelist giveaway. if you don't get enough entries, you can invite people and add them to your whitelist.
no need to delete it.