If you have been blessed and want to practically bless this ministry, you can do so.
Of course there is no obligation.
There is no particular amount required so pray and let the Holy Spirit guide you before giving.
Give, and it will be given to you. A good measure, pressed down, shaken together and running over, will be poured into your lap. For with the measure you use, it will be measured to you.
Take care and thank you.
A son of the Most High