yes marshmallow update is available in Vivo v3 max, you can follow the following steps:-
Charge your Vivo V3 Max to 100% to update Vivo V3 Max to marshmallow.
Then reboot your device.
Now you might get a message that marshmallow update or update is available.
Download the marshmallow update for Vivo V3 Max and you are good to go.
If you dont get a update.
Head to Setting.
About Phone>System Update.
Now search for marshmallow update for Vivo V3 Max.
If the update is available.
Now connect your Vivo V3 Max to internet to download marshmallow update for Vivo V3 Max.