Cannot download CS5 Suite

Ideally you should have backup installers just in case.   The direct download links on Pro Design Tools website (by permission from Adobe) may not work with Student/teacher or volume licensed editions.   If you had an individual license and you still have the serial number, it might work assuming you have an older operating system that can support it.   Be sure to follow the VERY IMPORTANT INSTRUCTIONS.

https://prodesigntools.com/all-adobe-cs5-direct-download-links.html

NOTE:  Creative Suite installers won't work on Sierra, High Sierra or Mojave without terminal workarounds.

NOTE 2: Creative Suite WILL NOT work on Catalina or Big Sur.

1 - https://community.adobe.com/t5/download-install/download-non-subscription-adobe-software/td-p/11919842

2 - Direct Download Links https://prodesigntools.com/tag/ddl MAY help
-you MUST do what it says in Note: Very Important Instructions
-https://prodesigntools.com/adobe-cc-2015-direct-download-links.html#download-instructions
-the prodesign links go directly to Adobe's file server, so this process will
--only work until Adobe completely removes the old version(s) from the server
.
IF/When you do have a download, be sure to copy it to AT LEAST one external device
-since Adobe does sometimes remove old versions from the server
-a usb flash drive or hard drive, or write to a DVD
-plus a text file containing your serial number if you have CS6/CS5