When putting your hours into PTCAS you will list each individual place you shadowed at and then describe it as inpatient, outpatient, etc. and PTCAS will also give you a spot to put what type of patients/cases you saw there (ortho, neuro, pediatrics, geriatrics, etc.). There is also two options for obtaining your hours - paid vs. unpaid. If you are able to find work as a PT Tech/Aide, you can get a lot of hours and get hands on experience working with patients, while also getting paid. If you are shadowing, you are strictly observing the PT and will have the opportunity to ask them questions about the patient/case. It's usually recommended that you obtain hours in various settings, but in my experience, it is definitely easier to find opportunities in outpatient clinics. Calling around to various places in your area is usually the best way to see if they are allowing students to shadow at this time
If you decide to work as a PT Tech/Aide, I would definitely check with the schools you plan to apply to and verify that they do accept paid hours. Most do, but every school is different! And when you do start getting your hours, it will be really important to keep a detailed list of the places you shadow, the names of the PTs you shadow, types of cases you see, and total # of hours.