The link you gave says:
The CV model is a natural fit for simulating bosonic systems (electromagnetic fields, harmonic oscillators, phonons, Bose-Einstein condensates, or optomechanical resonators) and for settings where continuous quantum operators – such as position & momentum – are present.
Which means you can have many, many different different matrix representations for the CV gates. They then point out:
The most elementary CV system is the bosonic harmonic oscillator.
This means that for any values of the scalar (non-matrix) parameters $\alpha, \gamma, \phi, z, \theta, \gamma$, you can just calculate the formula they gave you, using the following matrix representations for the creation and annihilation operators for a bosonic harmonic oscillator:
The number operator $\hat{n}$ is just $a^\dagger a$.
Keep in mind that any matrix representation is basis-dependent, meaning that you can take these matrix representations and (for example) diagonalize them, and they would be a perfectly valid matrix representation in a new basis. However the matrices I gave you here are quite "standard" for quantum harmonic oscillators.