You can't "handle" 5* or even 4* yet. Being able to play a beatmap well means you have at least 95% accuracy (shoot for even higher like 98%+) regardless of the combo. FCing maps shows a level of consistency that mashing through a song a full star level higher than what you can handle doesn't, hence why FCing and accuracy play a huge part in the ranking system. For now, I would focus on getting your accuracy fixed.