Apple Watch / Walkie Talkie - Can't invite friends

Hi, ( Sorry, im not quite good in english, I hope you can understand the problem anyways...)

Me and my friends have tried to connect Walkie Talkie togheter.

We already tried the guiding from Apple " Bruk Walkietalkie på Apple Watch - Apple-kundestøtte (NO) "

Nothing works, and when we tried to send invitation to each other - We can't recieve it.

Best Regards,

Karin