Hi @markus_m2 - XOVR is a US based ETF so is ineligible for trading within Europe. General rule with ETFs is if there’s no “UCITS” in the title then it doesn’t meet European requirements.
You might be able to find a compliant equivalent or a different fund that offers similar exposure.
Here’s a thread with some info on what’s available to T212 customers:
Stocks & ETFs requests Help - 
Stocks & ETFs requests - Trading 212 Community