Step 1 - Click on https://appstore.hikvision.com/ on your mobile phone.
Step 2 - Click to download Hik Connect
Step 3 - You can either navigate to your Download folder using a file browser app or simply begin the install by clicking on the completed download in your mobile browser.
Step 4- Android will ask you to grant permission to either the file browser or your web browser to install the app. Grant the permission and it should bounce you back to the installation screen. If not, navigate back to your Download folder after granting the permission to try again.
The app should safely install.