Is the certificate a housing booking?

No, and that is exactly the point. The Studhome certificate is neither a lease nor a firm booking: it is a proof of accommodation backed by a real address in a Colonies residence, meant for your visa file.

Concretely:

• Before the visa: the certificate proves where you will live, without committing to rent, a security deposit or booking fees. You don't pay for housing for a visa you don't have yet.
• After the visa: you choose your housing freely. If you pick a Colonies residence (browse availability city by city), your personal code gives you €100 off your booking fees.

You stay free: the certificate never obliges you to live with Colonies. And if you'd rather book firm housing before the visa, that's possible too; our guide on booking from abroad compares the options.