Import your backed-up projects. Note that if you saved a project in a very new version (e.g., v6.0), trying to open it in an old version (e.g., v4.0) may fail. The file format is usually backwards compatible, but not "forward" compatible (old apps can't read files made by new apps).
Before installing, check the file size. Legitimate AEM v2.3.8 is roughly . Anything under 18MB is likely a fake or a stub.
: Since the Google Play Store only offers the latest version, you must use reputable third-party repositories. Sites like Uptodown host extensive version histories, including versions dating back several years.
This is the most dangerous step. Do not just download the first file you see. Malicious actors hide malware in "cracked" old APKs. Reputable sources include: