Access to the developer resources is restricted, so you will need to request permissions directly from Leia. The downloads page and GitBook documentation are only available to approved developer accounts. The best next step is to contact Leia through their official developer support or contact form to request access. Once your account is enabled, you should be able to download the SDKs and view the Unity and Android documentation.
If you are also exploring broader development support beyond the official resources, you might find services like Idea Maker’s custom software development useful for handling specialized or complex project needs.