Toolbox .zip / .tar files: Where can I find Toolbox installables?

If I recall correctly, if you are your license administrator or financial contact then you can download all of MATLAB as an iso. When you open that, then IIRC the install will have a series of zip files related to reinforcement learning, probably 3 to 5 such files. You could then copy those into your directory that has the rest of your MATLAB installation archive files and use the setup program to install from there.

Alternatively, you go through the installer. In the step after you have logged in, the Advanced Options in the upper right will become active. You can select Download Only. After that go through the product selection screen and let the archives download. You can then copy the archive directory to another machine.

Historically, the pages to download matlab used to allow you to download specific products. That has not been possible for several releases now, and the toolbox is new since that time, so there was never a time when that toolbox could have its files downloaded directly.