The Crewlink course is only acceptable to Ryanair which actually (through an intermediary and some smoke and mirrors) gives the course. Although it is provided via Crewlink, the course is usually given by Ryanair personnel. Successful applicants will be offered a contract to fly with Ryanair but will always be employed by Crewlink. More than half all Ryanair cabin crew are employed this way and the proportion is rising every year.
Be warned: your wife will have a strong chance of either being fired or leaving because she cannot stand the pressure of this aggressive employer. I've seen figures that at least 25% will be either sacked or will quit in the first year. (Others say upwards of 60% but I have no way of knowing if this is true). Among reasons for being fired is failing to sell enough to passengers on board the aircraft. Your contract does not guarantee any basic minimum and you can be laid off for weeks, sometimes months. You pay for your uniform, don't get free meals and you are only paid while the aircraft is moving. Yet you are required to work several unpaid hours daily on ground and turnaround duties. You have little choice in where you will work and can be posted to Eastern Europe at the drop of a hat. Neither do you get expenses.
Getting fired can be exp[ensive and I've met kids at my local airport who are almost penniless afterwards. Ryanair makes outrageous deductions from final paycheck. You don't get your final month's sales commission, cost of uniform is deducted, and if you took advantage of the so-called "New Joiner's Allowance" (upwards of €1300) it's deducted from your final check. Ryanair won't fly you home either, just to the airport where you were based.
Be warned.