Access 365 run time deployment best practices

The answer to both your questions (Do we make some error? Or Access 365 runtime is really so huge?) is 'No'. Your XML is legit, and the Access Runtime should be in the ballpark of less than 200 MB. But, here is the catch: All products M365Apps-related products use a unified installation source. So ODT pulls down this unified installation source which contains all products like M365Apps, Visio, Project and the Access Runtime and is roughly 3GB in size. When running an installation (setup /configure) the setup engine only pulls the data it needs to install the specified product. That's why the Access Runtime Online Install is much faster as, it only pulls down what it needs. But with the /download switch, it always downloads the whole unified installation source. That's why you have the 3GB on disk. I'm not aware of any way to circumvent this behavior other than allowing online installs.