Choose for iOS or tvOS.
Look for the player option confirmed for the device you will use. Read its system requirements and separate license terms. Do not assume an Android package or downloader code can be installed on an Apple device.
Keep login methods separate.
An Apple account, an app-store purchase and IPTV credentials serve different purposes. Use the service access details only in the player fields intended for them. Contact support if the supplied method does not match the app screen.
Test your intended viewing path.
Try playback directly on the chosen device. Casting or AirPlay support depends on the app and receiving device and is not equivalent to a native Apple TV player. Check subtitles and audio output before relying on it for a long viewing session.