Released in 1966, Zimbo Trio's album Volume 3, the album on which this track is found, came out at a time when odd time signatures in jazz, and especially samba and bossa nova, were still pretty novel. I don't know of many before this. So that could explain why there isn't a whole lot of improvising going on here. Or maybe Rubinho was just holding it down and intentionally being understated. Either way, the bulk of the tune is the same bar or two orchestrated just a couple of different ways.
Spending just a little bit of time with the four examples above should give you a pretty good grasp of a common samba feel in 5/8. But if you want to play along with the recording, here is the transcription in full. The track starts at 22:11, and the transcription starts after the intro, when the bass line comes in.