Hi all!
@OliverRodrigues I can see files in the SharePoint Library (not in the entity's notes). And I've checked all steps from the documentation - all was done.
@OliverRodrigues @Sumaira I found an interesting thing: I repeated all steps for my second Portal with the entity "Case" (like in the documentation) and received the correct result. But! My 2 Portals are not the same:
1) My first portal (where I can't achieve the correct result) is "Starter Portal". My second portal is "Customer Self-Service" Portal
2) First portal I created from blank. Second portal I created from template
3) First portal was created in the trial tenant with trial Power Apps license. Second portal was created in another tenant with paid license (not in trial period)
4) Environment where first portal was created has CDS without Dynamics 365 apps. Environment where second portal was created has CDS with Dynamics 365 apps.
5) In portal settings for the first portal I have no entity forms for "edit". In portal settings for the second portal I have an entity form for edit, but only one - for the Case entity
So, I think that it is depends on what kind of portal we are using. I'm afraid that for Starter Portal there are no possibility to make integration with SharePoint with all features. Or maybe we should create an edit form in Model Driven app? But how? I can create only form for create a new record, but not for edit...