You have the possibility to transfer a domain from your old provider to us via the ZKM - for this you need an Auth-Code from your old provider.
As soon as you have this code, you can start a "Domain-Transfer In" in the ZKM under "Domain Overview" > "Register New Domain" > There you will ask for the auth-code from your domain.
Please note that you must create a handle for the domain before you transfer it.