Hello. Google for a provider and take out a subscription. Then there is a link and a password which is entered once in the pre-installed app. Or download other apps like Zattoo etc., which allow you to watch for free but with fewer channels.
The Zattoo APP is available in the Formuler Marketplace, native store of Formuler.
Teleboy should be available in the PlayStore.
so you can certainly use one of the two.
but the advantage of Formuler is their own IPTV APP, but that is a grey area!
I don't know the device, but it is possible to install Android apps by uploading the APK file via a USB stick.
You might get a better answer in the forum.
https://www.formuler-support.tv/