The official home of Basilisk is the Pale Moon project (basilisk-browser.org). However, the "portable" version is usually maintained by third-party packagers or can be created manually using tools like PortableApps.com Format.
Ensure you download the 32-bit version of Basilisk. Why? The final version of Adobe Flash Player (NPAPI) that works universally is the 32-bit variant. 64-bit Flash was always problematic and is harder to find. basilisk portable with flash player
Because you are using a portable drive, speed matters. The official home of Basilisk is the Pale
The "Portable" version refers to a build designed to run from a USB thumb drive or a local folder without needing installation. Ensure you download the 32-bit version of Basilisk