If there is no signed agreement does the contractual relationship default to Optional Service Contract Terms? https://www.upwork.com/legal#optional-service-contract-terms
So according to paragraphs 6.4 and 7.3, I can't upload my work to my portfolio on any website including upwork because I'm not an author as soon as Client pays for the Work Product? So the only way to avoid it is to agree with each client upon I am considered as an author as well, and Client approves posting, or am I missing something?
I understand waiving all the right to use, license, and so on. However, why not to leave a freelancer as an author with transferring authorship to the client as well. That way the freelancer can't use Work Product but can state that he did it unless other is agreed like NDA. I feel this rule can get 96.43% of upwork users banned and get sued for not having the rights to showcase the work to get new clients as they not considered an author. Isn't that feels wrong?
Dmytro, your understanding of this is incorrect.
In order to include something in your portfolio that you created on behalf of someone else, all you need to do is get their permission.
Also, you do NOT need permission from a site owner to link to their public website or to tell a prospective client to check out that site.
If you created a website, you are free to tell a prospective client to go look at it as an example of your work.
You do not need to have any type of ownership over the work in order to be able to do that.