Workout too hard

Hi, I am a 16 year-old boy. Here is my Stats:
Weight: 63kg
FTP: 262watts
5min: 319watts
1min: 481watts
5sec: 716watts
1sec: 1089watts
Trainer: Elite Zumo
Use Apple TV
My problem is when I do a workout (such as Neuromuscular and AC) I can’t seem to hold the power. I am doing TT-TUNE UP. The workout went as follows:
5min warm up
(1min@210watts, 1min@130watts)X2
(1min@260watts, 1min@130watts)X2
(15sec@315watts, 3min@230watts)x8
(1min@365watts, 2min@130watts)X2
5min cool down
I have this problem not just with this workout but with others as well. My HR reached 207bpm. I know you shouldn’t be restricted by your HR but it was over 200bpm for the majority of the workout that I did.
I hadn’t calibrated my trainer for 6 months (which I know is bad) and I was feeling the power was to high so I calibrated it through zwift. Here is what I don’t understand - when I do free rides I hold power fairly easily around my FTP. I can hold 300watts on a free ride much easier than on a workout. I think there is a problem with my Zwift, my trainer or me. Can anyone help?

Hi thanks for your reply. I can hold 300watts easier on a free ride than a workout. I would love to be able to hold 300watts for 20min. My fault, I should’ve made it clearer. I haven’t done a FTP test since the calibration. I’ll try that tomorrow to see if it changes anything. Thanks for your help. I’ll say how I got on.

Hi again, I did a FTP test and my FTP has increased to 265watts 3watt increase. My max HR was 216bpm.

•I struggle with Cruise Intervals 100%.

•Also the past AC workout I did it had me holding 395watts for 2min which is a pb for me. It was wanting me to the repeate the set multiple times. I couldn’t finish this workout.

•I can handle controlled cadence workouts pretty well and complete most of them.