There is an issue with IBM SPSS installing on Mac's Big Sur IOS. Known issue between IBM and Apple. There is a patch that can be used with SPSS v26 that can be downloaded from the IBM Support page. Users will have to create an account on the page before they can download the patch. This applies to v26 SPSS.
https://community.ibm.com/community/user/datascience/blogs/todd-peterson1/2020/11/20/spss-statistics-on-macos-big-sur-110