How to enable basic authentication for multiple documents?

Question

For some time now, Microsoft has been fighting against access to Office files via WebDAV (see e.g. Microsoft Office has blocked the opening of a cloud (Exel) or 2307 / 2306 breaks webdav interactions in office). I have identified the blocking of "Basic Authentication" as the cause of the problem. This can be reactivated in a workaround via local group policy for certain hosts. Procedure:

1. download templates for Office-related local group policies at https://www.microsoft.com/en-us/download/details.aspx?id=49030
2. execute and unzip the .exe file
3. change to the "admx" folder
4. copy the .admx files to C:\Windows\PolicyDefinitions
5. change to the subfolder "de-de"
6. copy the .adml files to C:\Windows\Policy\Definitions\de-de-de
7. start group policy editor
8. switch to User configuration -> Administrative templates -> Microsoft Office 2016 -> Security settings
9. activate the template "Admission of specified hosts to display prompts for standard authentication for Office applications"
10. enter the corresponding host name
11. save and restart the computer

Problem: With the procedure described above, a maximum of one document per Office programme (Word, Excel, PowerPoint) can be opened. As soon as, for example, an Excel document is open and another one is to be opened, the following error message appears: "Microsoft Office has blocked access to "XYZ" because the source uses a login method that may be insecure. This error message should no longer appear after the above configurations, as an exception has been created for the host. How can I use Office as intended again? Thank you and best regards.