: While Illustrator was 64-bit by this time, certain internal licensing and core components remained 32-bit.

If you need Adobe Illustrator CC 2017 (v21.0.0) for compatibility, follow these steps through the Adobe Creative Cloud Desktop App: Install previous versions of Illustrator - Adobe Community

– If someone owns a valid license, how to download and install older versions like Illustrator CC 2017 via the Adobe Creative Cloud desktop app (under “Other Versions”).