Can I still apply to UMD, College Park (priority deadline Nov 1st) if I take the SAT on October 6th (senior year), or will it be too late?
It should be fine but read your college’s admissions website carefully.
The College Board website includes a score release schedule so that you can know when to expect your scores. Also check the college’s admission website, as it may suggest ordering the scores to be sent before you’ve seen them.