This forum is about midi, not audio recording.

If you are planning to use midi, you are not clear as to how.

The easy way to achieve the stated purpose would be to connect the audio output of the piano to the audio input of the computer and record direct into Audacity, and save the result as an audio file. Job done? This will retain all the sound capabilities of the piano. This will be lost if you use the midi output of the piano, this will keep the midi data ONLY, and you will need to convert this back into actual sound elsewhere, using - you don't say. Hopefully NOT the WinDoze default synth?

More detail regarding your plans re MIDI would be a help!

Geoff

Cakewalk will do everything you want. And it's now free.

https://www.bandlab.com/products/cakewalk

Cakewalk may well do what you're looking for, it's a DAW system (Digital Audio Workstation) and it's capable of recording both MIDI and audio within the same project, like a multi-track recording studio.

I repeat my previous comment, the P85 may well be capable of some very nice sounds, and you may wish to keep those sounds available, in which case you'd need to record audio and not midi. If you record midi, you record ONLY the Note On/Note Off and similar technical data, not the actual sounds. Then when you play back the midi data, you'll need to apply a 'sound' to the data which may well not be as good as that produced by the P85. On the other hand, you may be able to use a MUCH wider range of generated sounds, either from hardware sound modules, or from digital facilities within the computer/software. This will be up to you, by all means experiment.

Of course, you can record midi information to add to your project, and then play that back assigning the midi data to a different sound source, by intention/choice to give yourself the much wider range of sounds that the P85 provides, which I believe is mostly piano family.

Regarding the audio, the P85 has 'Phones' output for audio, this is designed for headphones. This output MAY work with the audio (mic) input on your PC, but the levels may not be ideal. This will depend on the details of your keyboard, and your soundcard, and all you can do it try and see what it's like. If it's not ideal, we can find a suitable 'box' to fit between, or suggest a mixer, or something. But it might work OK right away..

Geoff

You should use DAW
The indie recording environment definitely has their appeal. Today's DAW and software platforms combine the fidelity of digital audio with the workflow and sound of analog recording setup: panel-based mixing environments, effect-based simulation tape and hardware, and synth's virtualization could not be found, drum machine and drum set.
You see: https://bedroomproducersblog.com/2015/11/11/free-daw-software/