If you want to launch apk packages on major platforms, you must sign them. Of course, unity already has this function.

First, use the genuine version (free version is ok), but don't use the cracked version, although this is ok, but for the sake of safety, don't use the cracked version, but also to respect the labor of others.

Second, when building, select the android platform, click playersettings, and there will be a publishing setting on the inspector panel, where you can configure signature-related operations. A, creating a new keystore; B, click browse keystore, and select the storage location; C, inputting a password on the password of the keystore; Confirm the password and enter the password again; D. Select New Alias in Alias to open the panel, enter the corresponding information, save and exit, and enter the password. At this point, the signature configuration is completed.

Third, open the box and sign it automatically.