It is not compulsory to retain the services of a real-estate broker (real-estate agent).
This being said, unless you are capable of handling on your own the purchase or the sale of a condo, and investing a lot of your time and efforts and possess specific knowledge in relevant fields, it is in your best interest to be assisted by a competent real-estate broker.
Since May 1st, 2020, mortgage brokerage has been supervised by the Autorité des Marchés Financiers, to ensure the protection of the public. Any hypothecary broker must maintain professional civil liability insurance, and abide by its code of ethics.
Once the apartment of your dreams in your price range found, the next step is to make an offer to purchase, either verbally or in writing. Although the verbal option is legally valid, it is better to formalize it in writing. L’Organisme d’autoréglementation du courtage immobilier du Québec (OACIQ) (the Quebec Organization for the Self-Regulation of Real Estate Brokerage) imposes a rule of ethics, namely that all acting real estate brokers must record in writing the intention of the parties to enter into real estate transaction.