@Tangeed
If you signed up for AllBlk directly with https://allblk.tv/, then you should be able to view on any supported device.
If you signed up for AllBlk through Roku, (ie. RokuPay), then you will need to view through Roku Channel (using a Roku device/RokuTV or Roku mobile app).
Also, if you signed up through Roku, make sure all your Roku devices/RokuTVs are using the same Roku account (email address) so that you can share the subscription amongst the "linked" Roku devices,
The benefit up signing up directly with the provider, rather than through Roku is the ability to watch on both Roku and non-Roku devices.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102