Samsung Galaxy S6 Edge can't activate

Hello!

I have a Samsung Galaxy S6 Edge(SM-G925P) and whenever I insert a sim card and click activate this device in settings it just keeps retrying and failing, also a weird message pops up whenever I restart the phone "Attention Power off your device, inser the service provider UICC that came with the device, then power on the device.".

I'm here asking for advice on how can I get it to work without buying a Tmobile sim(Im in europe).

NOTES:The device was originally from Sprint I think.