I am traveling back to Italy tomorrow but I forgot to print the boarding pass (I do have the PDF on my phone). I wanted to confirm whether I really needed to print it before going to the airport and that I cannot just use my phone. I have seen the other questions related to this but they seem to be very old.
Based on my personal experience: you cannot use pdf on your phone. But if you checked-in, chances are good that Ryanair won't charge you for printing your boarding pass. But don't do it at check-in counter, go to the Ryanair information counter.
Another option: you can try to print your boarding pass in a copy-shop at the airport if there are any.
I printed the boarding pass to be safe but still used the pdf on my phone to pass through all of the checkpoints. It does say that on Ryanair's website but at the airport in Budapest (to Milan, Italy), there was no need to show them the printed pass.
I wouldn't trust them with a 10 foot pole. I have the boarding pass on my Ryanair mobile app, but I am an American citizen with residency in Spain and have a residency card which may not be enough for money grubbing Ryanair which threatens to charge 55 Euros or 55 pounds (around the price of my round trip!) to print out a boarding pass (much more than the much hated Spirit Airlines in the States).
I am printing off the boarding pass but will try the mobile app first and see what happens. This really sux because who has a printer nowadays? Everyone does everything with their mobile. If this airline were not so freaking cheap and did not go where I want to go, l would be willing to pay more and not be subject to their numerous indignities.
Ryanair will not accept a PDF of your boarding pass on a phone, and are notorious for charging a lot of money for printing boarding passes at the airport.
However even if you have already printed a boarding pass you can still use Ryanair's new mobile boarding pass app.
The link takes you to a page where you can select Apple, or Android/Google Play to download.