Endless loop in the installation/purchase process

I try to purchase 16.0.3 as offered on the product web site

• I had downloaded the update already and want to use the full version instead of the last beta version.
• Installation OK, but on lauch I get the message → FrameMaker must quit because you're not signed in.
• I quit and start FM again
• → If you’ve made your purchase, please try again.
• I use "Buy FrameMaker at Adobe.com" on this dialogue.
• On the website https://www.adobe.com/ch_de/creativecloud/plans.html?plan=individual
  FrameMaker is not listed at all!
• I go to https://www.adobe.com/ch_de/products/framemaker.html and download again to get  a test/trial version and install it
• On start i get → Your FrameMaker subscriptio has ended. Renew your subscription at Adobe.com today
• Button Renew at Adobe.com leads me to
  https://www.adobe.com/ch_de/creativecloud/plans.html?plan=individual which is completely useless.
• → loop, endless
• Sign out, sign in has no effect on this endless circle
• Now I start up the last beta version and look, whether there is an update option
• Help > Updates is grayed out (which is reasonable for the beta version)

HOW can I make FM-16 trial-installation to run?