The tennis court is inside the club house of Sunshine City. You can arrive at the shopping mall (now renamed as MOSTtown) via MTR Ma On Shan station.
Just at the entrance of MTR station (correct entrance!), turn left and within minute of walk you’ll find CRcare as photo, the entrance is at the left side, it is just now change to the right hand side.
The entrance is next to CRCare.
After passing the club house with access control, turn left immediately via another entrance (without access control) to outside, the tennis court is just at left within 1 minute walk.