If it is an apartment in a lodging establishment, there are some exceptions regarding the landlord confirmation(Housing provider confirmation). This is because different deadlines for official registration apply to tenants in lodging establishments. A distinction is made between tenants who already have an apartment in Germany and have registered their residence there, and those tenants who do not have a residence in Germany:
Tenants in an accommodation facility who already have a residence in Germany do not have to register as residents in the rented apartment if the rental period is less than six months.
Tenants in an accommodation facility who do not yet have a residence in Germany do not have to register as residents in the rented apartment if the rental period is less than three months. Only if they stay longer in the apartment must register there officially within 14 days after the expiration of the three months.