Open the app. You may need to log in via phone number or social media. Ignore the "Update available" popup (tap "Later").
Navigate to APKMirror.com (most reliable). Use the search bar and type: TikTok Lite Tiktok Lite Version V21-5-1 Apk Download Mirror
Filter the results. Look for an entry specifically labeled: TikTok Lite 21.5.1 (arm64-v8a) (Note: Check the "Variant" column—choose the one matching your CPU: arm64 for 64-bit phones; armeabi-v7a for older 32-bit phones). Open the app