When the message is seen as " this player has reached the maximum limit" this is because :

He already received 6 galleys on the day as a free gift from other players.

A day in the game will be determined by the time zone operates on and this is set as Greenwich mean time + time zone of your area.

During this time you can only receive 6 galleys of free resources of 50.000 which they can be sent as one type of resource or all types but not exceeding the 50.000.

Trade galleys are determined by the upgrades made and for that you need to upgrade the : 
*Port
*Harbor

 for speed of your galley :
*Lighthouse

Trade of resources amount will depend on your number of galleys and capacity of your galleys.

Trade has no limit as long as you have free available galleys.

I hope this helps.