Corrupted attachment with CEM (PEC)

Dear all,
i configured the accout of my CEM (PEC) in my eM Client with the setting suggested by my CEM provider, but when I download messages with attachments (.pdf,.zip, etc.), the attachment are corrupted.

If i check the same emails in the webmail of the CEM provider or using a different email client, for example Thunderbird, I’m able to download attachment correctly.

Do you have some suggestions to fix this issue?
My eM Client version is 8.0.3385, free edition