I think I figured it out after 2 hours of struggles.
I have a macbook pro 2015 running Big Sur 11.2.3.
I already had SPSS 26 installed but it was no longer working since I updated to Big Sur. So, here are the steps I followed:
I uninstalled it (only do this if you have a serial number for the software... my university provided me with one).
Then I went here to get the Fix Pack 2 from IBM (it's free):
https://www.ibm.com/support/fixcentral/swg/downloadFixes?parent=SPSS&product=ibm/Information+Management/SPSS+Statistics&release=All&platform=All&function=fixId&fixids=26.0-IM-S26STATC-Mac-FP002&includeRequisites=1&includeSupersedes=0&downloadMethod=http&source=SAR&login=true&login=true
[the file to download is called "fix pack: 26.0-IM-S26STATC-Mac-FP002"].
It initially wouldn't let me download it but said they would email me and about half an hour later I received an automated email and then when I went back to the fix centre, it was working and I managed to download the fix pack.
It took some time to install because I needed to update java as well as download an IBM download director. Felt like the year 2000. But persevere!
Once you've downloaded it, install the Fix Pack 2 by right clicking and selecting "open" (seems obvious but it makes a difference). This will reinstall SPSS 26.
You should be able to run the programme and then insert your serial number and hopefully it will work!
#SPSSStatistics#Support#SupportMigration