Assumed spout was twist on because wasn’t visible. Turning caused threaded grooves. New spout won’t slip on, gets caught up in grooves. Can this be remedied?

When you turned the spout, it likely caused some burrs on the pipe next to the groove. I would just take some sandpaper and make sure the area around the groove is smooth.

Smoothing out the burrs and grooves with sandpaper should solve the problem.

I agree with both of them above