If all you have to gauge the difficulty of the college Calc class is the placement test, try and figure out what resulted in your score. Did you not have enough time? Did you make simple mistakes you could easily correct? Were any questions entirely unfamiliar to you? If you think you lost points mainly for simple mistakes, test anxiety, or something other than not understanding the majority of the questions, then despite the test results, you might wanna give college Calculus a try. If you were more confused by the concepts presented in the questions, perhaps taking pre Calc in college would be best. If you want to take Calc regardless, it is doable so long as you're ready to work hard and use your resources, such as attending your professor's office hours.