Apps broadly fall into one of two categories: Charging, &; Charger discovery & route planning. You won't require all of these, but you will require some.
Charge point operators will typically provide an app enabling use of their own charge points, & is generally in addition to other means of use (account tags / cards, or contactless payment cards). Apps have the benefit of providing real-time status, pricing, support, notifications, & other useful information - of particular use are notifications which may notify you as to time remaining before imposition of overstay fees. These apps can also be used for charge point discovery, however it is important to note that they will likely be limited to displaying only those charge point operators which they are compatible with.