A1 is the lightest subcategory of the open category — "fly over people". It covers C0-class drones (under 250 g) and C1-class drones (under 900 g). Incidentally overflying uninvolved persons is tolerated, but must be avoided whenever possible, and with a C1 drone you must not overfly uninvolved persons at all.
Even in A1 there is a hard line: flying over assemblies of people is never allowed. To fly a C1 drone, the pilot must complete the A1/A3 online training and pass the exam — exactly what this platform prepares you for.