how do I install pix4d on the Phantom 4 pro v2?

If you are asking about the ordinary P4 pro v2, you install it on your phone or tablet the same way you install any app.
Here it is:
https://www.pix4d.com/product/pix4dcapture

If you are talking about the P4 pro V2+ with the controller and integrated screen, you are out of luck.
You would need to get  a non+ controller to run Pix4D.

Thanks for the reply I am talking about the P4 pro V2+ with the controller and integrated screen.
What is and how do I get a non+ controller to run Pix4D?

Hi there. Thank you for reaching. If you are using the DJI Phantom 4 Pro Plus (built-in screen), we do not recommend using this 3rd party application as we don't have any guarantee for its stability when in use on the said unit. If you want to do mapping, kindly please check the GS Pro instead. Thank you for your understanding and support!

DJI Paladin Posted at 6-6 19:27
Hi there. Thank you for reaching. If you are using the DJI Phantom 4 Pro Plus (built-in screen), we do not recommend using this 3rd party application as we don't have any guarantee for its stability when in use on the said unit. If you want to do mapping, kindly please check the GS Pro instead. Thank you for your understanding and support!

we do not recommend using this 3rd party application as we don't have any guarantee for its stability
That makes no sense.
If DJI didn't want users to have 3rd party apps, they wouldn't have made the SDK available for 3rd party app developers.

jrjjisland Posted at 6-6 15:45
Thanks for the reply I am talking about the P4 pro V2+ with the controller and integrated screen.
What is and how do I get a non+ controller to run Pix4D?

The controller you would need is the GL300L and you would need a phone or tablet to go with that.
Probably the best way to get one would be to check ebay etc for someone that's lost their P4pro V2 and is selling the accessories.
Once you have the controller, it only takes a minute to link it to the drone.

But be aware the the controller for the original P4 pro is not compatible with your drone.
The GL300 is compatible.

Labroides Posted at 6-6 21:02
The controller you would need is the GL300L and you would need a phone or tablet to go with that.
Probably the best way to get one would be to check ebay etc for someone that's lost their P4pro V2 and is selling the accessories.
Once you have the controller, it only takes a minute to link it to the drone.

Thanks got it.
Sounds like I am just out of luck using Pix4d.

DJI Paladin Posted at 6-6 19:27
Hi there. Thank you for reaching. If you are using the DJI Phantom 4 Pro Plus (built-in screen), we do not recommend using this 3rd party application as we don't have any guarantee for its stability when in use on the said unit. If you want to do mapping, kindly please check the GS Pro instead. Thank you for your understanding and support!

Thanks for the info.

Labroides Posted at 6-6 20:57
we do not recommend using this 3rd party application as we don't have any guarantee for its stability
That makes no sense.
If DJI didn't want users to have 3rd party apps, they wouldn't have made the SDK available for 3rd party app developers.

Hi, Labroides. Thank you for your response and my apologies for the confusion. The statement that I had posted is for the DJI Phantom 4 Pro plus (Built-In screen) as we cannot guarantee that it will work properly on the said RC. Thank you for your kind and understanding. Fly safe!

jrjjisland Posted at 6-7 02:26
Thanks for the info.

You are most welcome. Take care and happy flying!

DJI Paladin Posted at 6-7 22:52
Hi, Labroides. Thank you for your response and my apologies for the confusion. The statement that I had posted is for the DJI Phantom 4 Pro plus (Built-In screen) as we cannot guarantee that it will work properly on the said RC. Thank you for your kind and understanding. Fly safe!

It's kind of pointless recommending against using a 3rd party app on the + model when it's not possible to install the 3rd party app on the + model.

Labroides Posted at 6-8 03:39
It's kind of pointless recommending against using a 3rd party app on the + model when it's not possible to install the 3rd party app on the + model.

We totally understand your point, Labroides. Please let us know if you have inquiries or concerns and we are more than happy to help. Thank you for your continued support!

Joba11 Posted at 9-1 08:23
https://youtu.be/WQXBNhD50NY

ı can not install pure APK. There is a message on screen. This application is not authorised by dji

Very poor DJI. Everyone who has bought the top model and controller are left behind with ability to run Pix4d software.
Is there hope of help from dji getting this sorted?