Try these steps:
1. Grant permissions (contacts, storage and accessibility service)
2. Click on a contact in the list in the middle of the main screen to start the download.
After some seconds WhatsApp should start and is navigated to the profile picture.
Then our app should start within some seconds. If this doesn't happen, something goes wrong.
Please tell us, where the process stops.
Else we cannot help you!
Our app needs so many permissions, because WhatsApp stores the
profile pictures in a private folder.
The root-variant can directly open this folder, so it doesn't
need additional permissions.
The "normal" variant needs to access your contacts to offer you
a list from where you can choose whose profile picture you want
to save.
Then we need to have access to your storage to actually
save the profile picture there.
Finally we need the accessibility
service to automate interactions with WhatsApp and the android os.
All the data we access will only be used to save the profile
picture to your gallery.
No, of course not. All the pictures stay on your phone.
We only collect anonymized crash reports to fix bugs.
We have corrected this error.
Have a look at the troubleshooting options
(under Help or menu -> Settings).
There you will find the setting "Delay".
Increase this value until the picture is no longer black and the overlay is gone.
As our app is still under development, there might be bugs.
If you found one, report it directly in the app by clicking on
the "feedback"-button.
If it is not possible to do so,
write an email.