I will probably have the Resmed Air Mini CPAP machine with me. Have you found problems with the machine itself and using it in albergues in Spain?
I cannot speak to the reliability of that particular machine, but having used a CPAP on the Camino for my two most recent pilgrimages on the Iberian peninsula, I can assure you that you are unlikely to find any major difficulties.
Most people do not mind the noise of the machine, although I have had one person object to it. That was rather ironic, as it was the same individual who had disrupted the dormitory earlier in the evening with his alcohol-fueled snoring.
If I booked a bed in an albergue, I let the hospitalero know beforehand that I would like a bed near a power point. Otherwise, I requested that when I arrived. It was never a problem, although there was one hospitalero concerned about how noisy the machine was going to be. He was satisfied when I assured him that it would be quieter than my snoring if I didn't use the machine.
Not every albergue has power points in the dormitories. San Anton, which does not have electric power at all, comes to mind. If you did want to stay at such places, you will need a battery pack that will keep the machine going for six to eight hours, depending on how much sleep you think you will need to get.
I have seen pilgrims carry their machine in the case provided by the OEM. My observation is that these have a lot of wasted space, which I would rather avoid. For my machine, I purchased a padded case that is just the right size for the machine and its accessories. less the air hose, which I carry in a mesh bag.
It normally takes about 30 minutes in the morning for my machine to complete its drying routine, which I try to start as soon as I wake. This adds a little delay to getting away, but it is something that I got used to quickly enough.
That's all I can think of right now. If there are other things you want to know, just ask.