Welcome to the forum!
Camping is one of the controversial topics for this forum, so be prepared for some negativity. There are however a handful of members who do camp, hopefully a few will be along to give some decent pointers.
Having researched this topic (because I also intend to camp at times) the answer to your question would appear to be 'maybe'. In addition some may let you shower but not have place for your tent: in another words you may be able to shower before leaving town to carefully wild camp for example. Sometimes it's because they genuinely have no place, at others it is because of regulations. At Bruma on the Inglés I was told that it was illegal to allow us to camp, but I am unsure if that was a local (town) regulation, a regulation specific to the Albergue licence, or if that applies to the whole of Galicia.
I've copied this from another thread, it was about the only useful item on that particular one.
If you click on the camping tag under your thread you will find other posts.
As always if you set up late and breakdown early, and practice the Old Creed of 'leave no trace' that the majority of us follow you shouldn't have any real difficulties.