ik kan ARW. bestanden niet in photoshop 21 als mediabestand toevoegen

I was able to install Camera Raw 18.7 for Photoshop Elements 2021 after doing the 18.7 Camera Raw install like you did by going to

C:\Program Files\Common Files\Adobe\Plug-Ins\CC\File Formats
 

and copying that File Formats folder and replacing the File Formats folder in

C:\Program Files\Common Files\Adobe\Plug-Ins\Elements 19\File Formats

sample a6700mcamera raw file from here:

https://raw.pixls.us/

Your camera requires ACR 15.5.   Even if we could find that version, I’m not sure that it will install in Elements 2021.  I just failed to install ACR 16. 

Your alternative is to convert  your raw files to .DNG format, using the free Adobe DNG Converter. 

(Or you could upgrade to the latest version of Elements.  There should be some holiday (Black Friday) sales soon.)

i have photoshop elements 2021 

Do you get an error message? If yes. please post the message here word-by-word.

Which version of Camera Raw do you have installed?

Which type of camera do you use?

Check here which version of Camera Raw, Lightroom etc. you need to work with RAW filed from your camera.

Cameras supported by Camera Raw | Camera Raw