The original conlang author of Mando'a was inconsistent in spelling and pronunciation, which makes it challenging to determine exactly how to pronounce each letter. (I've tweaked my own version of standardized pronunciation numerous times.) It's also impossible to know how close the romanization of the words are compared to how it would be spoken by a "native," especially given spelling variations, obvious errors in the pronunciation of words (the pronunciation of "hibirar" given as [baj-hib-EER]), and pronunciation differences of similar letter combinations in various words. For example, the pronunciation of "yai'yai" is given as [YEY-yai]. Does the pronunciation of "ai" vary depending on where it is in the word? Or for "ori'vor'e," it's [AW-ree-VOHR-ay], but for "ori'dush" it's [OHR-ee-DOOSH] — what is the correct pronunciation of "ori"? Is Mando'a really not easy and regular and people have to memorize the pronunciations like we do in English?
Because of the number of different people from different regions who can become Mandos, it is reasonable to think of speaking Mando'a like speaking English: While there might a "preferred" way that certain groups recommend for pronouncing words, when conversations actually occur, every person who uses it puts their own spin on it.
Quotes about pronunciation from the author, including posts about the variety of accents: https://sites.google.com/view/hibirarmandoa/bajur/mando-droten/pronunciation/from-traviss
Tips for pronouncing Mando'a, including IPA and printable cheat sheets: https://www.tumblr.com/project-shereshoy/680019849037185024/pronouncing-mandoa
This is one attempt at standardizing sounds (from Mando'a Lessons): https://www.youtube.com/watch?v=-wRs65XyvHI
Playlist of 1100 words from the basic dictionary spoken, divided by letter; mostly follows the pronunciation tips suggested in the Mando'a Lessons videos: https://www.youtube.com/watch?v=YQfPCIh5KGM&list=PL7mXLZR0kBGVOYe-vIN032uFe_cZg-wKu
Scroll this page to find links to audio and video resources: https://sites.google.com/view/hibirarmandoa/bajur/hibirar
These notes are compiled from posts by various members of a Mando'a language group that I'm in.
The apostrophe (called a beten) in Mando'a is multifunctional:
Sometimes it indicates a glottal stop, /ʔ/ or the small stop in the English "uh-oh."
Sometimes it's pronounced as a vowel like /i/, /o/, or /ə/.
Sometimes it represents dropped letters.
Sometimes it serves only to differentiate similar words.
Sometimes it's meant to separate syllables.
Sometimes it does none of the above.
The simplest way to figure out how to pronounce the beten is to look up the pronunciation in the dictionary.
If that isn't handy, as a general guideline:
If the beten is between vowels, it's a glottal stop (like in mando'a) and indicates that the letters are pronounced separately.
If the beten is between consonants, or a consonant and a vowel, check the pronunciation guide to find out how what to do. In several words, it looks like it ought to do something, but it's actually ignored. In burc'ya, for example, you'd think the beten indicates that the c and y are pronounced separately, but they aren't; instead, "cy" is pronounced exactly the same as in burcyan, as /ʃ/ or [sh]. In other cases, it might be pronounced as a vowel (like in dush'shya, where it sounds like /i/ or [ee]).