Searching for and downloading an "Adobe Illustrator CS5 Portable Free" version is highly discouraged. Adobe has never released or authorized a "portable" version of Illustrator CS5.
An official Adobe subscription provides regular security patches and feature updates. With a CS5 Portable version, you are stuck with a 14-year-old codebase that is vulnerable to modern exploits and incompatible with new file formats (like the latest .AI or .SVG standards). Better Alternatives to Illustrator CS5 Portable adobe illustrator cs5 portable free
As for the free aspect, I must clarify that Adobe Illustrator CS5 is a commercial software, and as such, it is not available for free. However, there are some possible scenarios where you might find a free or discounted version: Searching for and downloading an "Adobe Illustrator CS5
Vector painting that mimics real-world brush strokes. With a CS5 Portable version, you are stuck