@kl.honda It's honestly a bit strange that Assemble still advertises this feature on their website, because I've never heard a single person from Autodesk mention that this integration exists... You can look at the Assemble Point Cloud Demo on YouTube (Called "Assemble Systems & Point Cloud).
I could be wrong, but if it's anything like their Procore integration, you will first need to have a subscription to the BloomCE platform, then you will have to contact Assemble to let them know you want to enable this feature in Assemble. There will more than likely be an additional charge to enable this module (as is the case with their other offerings like the Procore integration or the Assemble Schedule Integrator app).
On the Assemble Systems website, you can request further info about the Assemble + Point Cloud, and that should get the ball rolling if you're seriously interested in utilizing Point Clouds with Assemble.