Source: Regional Express (Rex)
My interpretation is:
“You can try this, but it might not work. If it doesn’t work, you’ll have to call us. And you must acknowledge this message before we can allow you to proceed with attempting this thing that might not work.”
It seems incongruous to flag potential failure. And even odder to force customers to acknowledge the potential for failure before embarking on the transaction in the first place.
In fairness, this message now appears to have been removed. Perhaps the airline has gained greater faith in its IT capability.