Do not download "GTA San Andreas PPSSPP 100 MB" files from untrusted sites – they are likely scams or viruses . If you want to play San Andreas on mobile, buy the official Android/iOS version from Google Play or App Store.
Search for "GTA San Andreas PPSSPP CSO highly compressed 500mb" – a better middle ground. Gta San Andreas Ppsspp Zip File Download 100 Mb
If you find a direct download link, click on it and select a download location on your computer. The file you are looking for is usually named something like "GTA San Andreas PSP.zip" or similar, and it's around 100 MB in size. Do not download "GTA San Andreas PPSSPP 100