Crystal Reports error when deployed..Could not load file or assembly 'log4net'

I know this question came here several times as here

This is exactly the same question, but there, the answers seem to be for web applications (I don't know what is IIS, but from my searches, it is only for web applications?). In my case, I made a local application.

I use VS2017, and Crystal Reports 2020. From other posts, I read that I need to install distributives, but as I understood distributives may be only needed for me (create/edit reports), and not at customer's?

I also tried to install Crystal Reports Viewer on computer, it doesn't change anything.

Edit : I see someone voted to close the question : This question doesn’t meet a Stack Overflow guideline.

Is it possible to have an explaination about it? Is there another stack I wouldn't know for Crystar Reports questions? If that's a problem I can delete question, but would like to know where to ask (SAP support is really a shame, 2 weeks I wait an answer, but no way).

Solution

So I finally got an answer from SAP (on SAP Community). There are many bugs/limits on Crystal Reports for VS :

You may never make a Release with "Any CPU". If target computer is 64bits, you may do it for 64 bits only.
SAP Crystal Reports, Developer Version for Visual Studio .NET does NOT support Express Editions of any version of Visual Studio
Use the Windows Viewer, WPF viewer has not update much.

-So for making reports you need to buy a licence. -If you own an Express version of VS, you can export reports at PDF format, but no any preview is possible in your application.

A bit a shame that SAP acts so, because when I talked with commercial before buying, they ensure there is no any problem. Only after when facing the problem it is visible. (Excuse if there is commercial information, but these informations may be known by users and potential customers I think).