@billyblaze
The walk to the station is 1.4 km (less than 1 mile). It takes 15-20 minutes and it is all flat.
The trains are very frequent, at least two or three per hour depending on the time of day. All the trains stop in Nice.
https://www.google.com/maps/dir/Gare+de+Cannes,+Place+Pierre+Semard,+Cannes,+France/Cruise+Terminal+•+Sainte-Marguerite+island,+Cannes+-+Île+Sainte-Marguerite,+06400+Cannes,+France/@43.5502186,7.0106867,1676m/data=!3m2!1e3!4b1!4m14!4m13!1m5!1m1!1s0x12ce8192598a6071:0xcec533c63c2ab8ab!2m2!1d7.019606!2d43.553758!1m5!1m1!1s0x12ce818585608013:0x604f21ba03a8f54f!2m2!1d7.0142395!2d43.5466383!3e2?hl=en&entry=ttu