A TV build and a phone build of the same app can behave differently.
The first question
Ask the seller how Android TV IPTV players works on your device, in your location and within the stated plan. A TV build and a phone build of the same app can behave differently.
Proof to request
Check remote focus, back behaviour and the on-screen keyboard. Ask for a current source page or written order summary, including the currency and any player activation fee.
The decision
Installing an unverified APK or the wrong device edition. If the answer is unclear, use a trial or a shorter period before making a larger commitment.
What to do next
Open the relevant brand page and check the original supplier information before ordering. For a technical issue, write down the device, player, connection and one reproducible example. For a price question, ask for the full charge in the currency you will pay.