CS5 was built in 2010 to run on Win XP/Vista/Win7, not Windows 11.
Technology & computers have changed a lot in 15 years, but CS5 hasn't kept pace with those changes.
CS5 REPLACEMENTS:
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FREE Acrobat Reader -- view, comment, print & sign PDF.
https://www.adobe.com/acrobat/pdf-reader.html
Paid Acrobat Pro -- the complete solution for creating and saving PDF.
https://www.adobe.com/acrobat/acrobat-pro.html
Photoshop Elements or Premiere Elements (3 year license, no subscription needed).
https://www.adobe.com/products/photoshop-elements.html
Creative Cloud Photography Plan:
https://www.adobe.com/creativecloud/photography.html
Creative Cloud Bundles & Single Apps for mobile, web & desktops
https://www.adobe.com/creativecloud/plans.html
Supported Adobe apps work on these systems:
- Windows 11 (64-bit) versions 24H2, 23H2; Windows 10 versions 22H2, 21H2;
- MacOS 15 (Sequoia), 14.7 (Sonoma), 13.6.7 (Ventura).
- https://helpx.adobe.com/creative-cloud/system-requirements.html
NOTE: MS is ending Win10 in October. Apple will release macOS Tahoe later this year.
Hope that helps.