You shouldn't have to activate anything - it should just work.
Do you have a connection to a local network/signal bars?
Are calls and texts working?
What are your APN settings?
However, note the following...
Unfortunately many people still seem to have problems when trying to use roaming services for some reason and nobody from 48 has ever explained why or provided a guaranteed fix.
As such, the usual generic advice for roaming issues applies...
If your SIM predates January 2023 then maybe get a replacement in case it helps with roaming issues:
It may be worthwhile reviewing these two threads in case any of the suggestions help to avoid roaming problems:
If you still have problems then you'll probably need to contact 48 support for further assistance.
See the links in my signature below.
