Man, I hit that wall too after seeing so many clips about 'Apocalypse Z' on TikTok. A bunch of us were in the same Discord and the general consensus is, it's kind of a no-go for a truly free, legal stream. You'd think with so many podcasts out there, maybe one of those audio drama networks would have picked it up, but I haven't found it.
What worked for me was the library route, though it took some patience. I signed up for Libby using my library card and just had to place a hold. Took about three weeks, but it eventually came through. That app is a lifesaver for audiobooks if you don't mind waiting your turn. Some people also mentioned their libraries use Hoopla, which has no wait times, but mine didn't have it there. It’s a bit of a digital scavenger hunt depending on where you live.
Otherwise, Audible is the obvious spot. Not free, but they do that one-free-book trial thing which is how I ended up listening to the sequel. Honestly, after listening, I felt the production quality was worth the credit. The narrator does this gruff, exhausted voice for the main character that really sells the whole diary-entry feel. You can sometimes find free codes from the narrator or publisher on social media, but those go lightning fast. I just got tired of hunting and used a trial.