The notary in Spain is a party occupying a public position. They check the identity of the parties involved in the purchase and make sure that the money involved in the transaction is traceable. The notary however has no responsibility regarding the content of the deeds drawn up. For example a notary will not check if there is a mortgage on the property, this alone would be a good reason to get your own lawyer.
Before signing the deeds at the notary, the lawyers will have made up all the necessary documents. When the notary gets in he will check the identities of the buyer and seller and read the documents (partially) in Spanish. If nobody objects, the deeds will be signed. At that moment the necessary payments will be made, usually by check and the keys handed over.
After signing, a copy can be obtained of the deeds “copia simple”. Your lawyer will make sure that the necessary taxes will be paid and that the property will be properly registered.
A few days later the lawyer can pick up the original title deeds “copia autorizado” at the notary.