How can I find HD channels on the Samsung Smart TV?

We have a new Samsung Smart TV with Datelit connection. This now shows a notification every time we turn it on or switch from Netflix etc. To FreeTV again that the TV can receive HD channels but can't find any:

Ooops

the HD + app has been installed, but there are no HD + channels in the channel list. Please perform a channel search again and make sure that this time all channels are searched for

We have repeated the channel several times and reset the TV to the factory settings to set it up again, but unfortunately still no HD channels. Can someone tell us what we're doing wrong or at least how we can get the notification away?
I thank you in advance for all tips!

Do you have HD +? So you subscribe or pay for HD +?

Search via "All channels", if you only have free-to-air search then no paid channels will be saved

Yes, we got the HD + subscription for 6 months when we bought it