Did the SIM activation process go ok? Are there any errors on the phone? What networks do you see if you do a manual scan/search? What happens if you try to connect to 48? Is the phone unlocked for use on any network? What make and model? If necessary contact 48 support tomorrow for more advice/assistance. See the link in my signature below.
Hope this helps.
I am not a 48 employee so if you need to contact 48 support then use option 3 or the chat facility here.
It seemed to go ok, I got a message on the site that said since I was with 48 before, I didn't need to do anything else. There aren't any errors, but when I try to join manually it says 'selected network is unavailable'. (A bunch of networks show up when I scan). The phone is unlocked. It's a Huawei p20 lite.