Hi @aktivido,
Based on your description, it seems that you are on a free demo account.
This is different than a free trial account. The trial accounts have 30 days free trial after which point these accounts become a regular, paid account.
The free demo account has a lot of limitations and the main purpose of it is to allow users to explore the platform and see if it’s a good fit for them.
If you are on a free trial account, I would suggest contacting the awesome folks at Unbounce support directly. I’m sure they’ll help you set up your domain.
Best,
Hristian