This information is misleading and should be removed. The matching power supply unit with 2-pin plug is of course included and can be used without any adapters.
It is a pity to read that your FRITZ!Box 6850 5G did not come with a power cable. Please send an e-mail to fritzhilft@avm.de with the ID #7095361 so that we can send you one. Please give us your name, address and telephone number.