Acrobat Integrated Browser is old and outdated. Can't get past corporate security due to age.
looking at the KB article https://helpx.adobe.com/acrobat/kb/forbidden-error-while-using-Fill-and-Sign.html it blames the network, but I have a different issue.
I'm getting the same error message, however, this is due to the fact that the integrated browser inside the adobe program is an old version and blocked by our corporate security system. the answer of "Connect the machine to a different network." isn't an option when you go through a cloud security service.
can we get a hold of developers to report this issue and get it fixed?