He/she wants to sign a contract with another operator.
Yes, but the landlord has his own contract with the internet provider of his choice. And expects the tenant to pay for it if he/she uses the Net.
It is written in the rent contract cited by the OP:
w przypadku zawarcia umowy."
In case the contract is signed. What kind of contract? Landlord`s with the provider, I presume. If it`s UPC, their contracts are valid for a year or even two. I have a two year contract.