Hi n welcome,
One of the great things about ebikes is the motor can compensate for fitness
mine does at least..
Depending on your choice of bike spares can be as easy as opening an ebay or ali express search page with the details on a label or as tricky as finding hens teeth.
#1 maintenance tip - If you own a power washer dont use it on your bike.
#2 Your battery is what needs the most maintenance, learning how to recharge to extend its life and get the most out of it, so dont recharge after every 5 mile trip to the shops etc..
If a hub drive just ensure the cable entry point through the axle has its cut off aspect pointing down! If pointing up even if covered water will collect and seep into the motor. Other than that its good to go and will probably run forever..
Most importantly have fun with the bike.