If you've never sideloaded an app before (install from a source other than Play or Galaxy store), it's important to make sure the file is safe and contains no malware. The APK mirror site below explains the security checks they perform. If you have some king of antivirus on your phone, it should also scan the file.
1) Dowload the APK from this site to your phone
https://www.apkmirror.com/apk/samsu...rience-home-touchwiz-home-12-1-05-11-release/
2) You will be prompted to allow downloads from whatever browser you are using (since it's not from the Play Store)
3) When the download completes follow the prompts to install.
4) You will be prompted to allow this file to install (since it's not from the Play Store) Once the install completes, you're good to go.