The following information I got from the mantisonline.de website. Whoever owns that website, if you are reading this, thank you for starting to translate some of the caresheets! When I am on the mantisonline.de website and I can't find a care sheet in English I use the lousy (cough) Google translator.
Popa Spruca Care:
12 hours of daytime temperature: 25 - 30 °C
at night: not under 20 °C
Humidity during the day: 50 - 60 %
Humidity during the night: 60 - 70 %
Again, information courtesy of the mantisonline.de website.