The simple answer is to look at your by-laws and check with your committee, strata manager or building manager. Some blocks require owners to book a move so that they can avoid the lifts being used when people need them most (e.g. when they are going to or from work). Some blocks also want the lifts to be protected with covers to prevent damage from furniture.
Installing a clothes line probably needs strata committee approval as it may be a minor renovation affecting common property. You might even have a by-law preventing drying clothes on balconies, so once again, checking your by-laws is where you start.