As you have uploaded the images directly to Pix4D Cloud for processing, a default processing template was applied (more info here). When using the Pix4Dmapper solution, the 3D Maps template is applied, where indeed the point cloud file in the .las format is generated by default. Then, it can be downloaded separately from the other outputs in the Files tab, under Results.
However, when the size of an output is very big or when specific camera/processing options have been selected, the output is split into sub-files (more info here). These sub-files can only be recovered by downloading the project folders (Export to Pix4D Desktop option). I suspect this is what happened with your point cloud.
Could you try downloading the project files and let me know how it went?
If this does not help, could you share the project link? More info here.
Note that our fair usage policy only concerns the number and size of projects processed on the cloud per month (15 projects/month of 150 images at 15 MP), not the available outputs.
Have a nice day