alpha channel uploaden

Can someone tell you how to upload an alpha channel?
When uploading a quicktime movie I get the following message:

We accept Quicktime MOV files over 5 seconds long encoded in one of the following:
Photo JPEG, ProRes, H.264.

I would just like to upload an alpha channel.
I regularly downloaded alpha channels, and then I just get .mov files, what goes wrong?

Use ProRes 4444 with alpha channel or render a separate Luma Matte in ProRes422 and upload it together with your RGB video in a zip.

Thank you for your answer.
The problem is in the ‘ProRes444’, I don’t have that output option. I am using AEcs6 and PremiereProcs6.

I’ve turned google inside out, but I can’t really figure out what’s the problem why i don’t have that option.

ProRess444 seems to be something from Apple? I have a windows machine.

I’m going to see if I can make a separate Luma Matte, as you suggest.

I would find it more convenient if I have one output file, because I have multiple alpha channels in my package.

Thank you in advance.

Early versions of After Effects and Premiere Pro do not have “ProRes” codec. If I’m not mistaken, it has appeared since the CC 2019 version