Adobe Muse

Adobe Muse reached its End of Service date in March 2020.  And the support community for Muse no longer exists.  It's essentially a dead product now.

https://helpx.adobe.com/muse/kb/adobe-muse-end-of-service.html

I can't in good conscience recommend that anyone keep using Muse for current projects.  The web has changed too much and Muse is unfit for use.

Depending on your needs, there are other tools you can use instead:

CODE EDITORS:
-- Adobe Dreamweaver CC - https://www.adobe.com/products/dreamweaver.html
-- Codespaces (free, browser-based) - https://github.com/features/codespaces
-- Nova (Mac only, formerly called Coda) - https://nova.app/
-- Pinegrow - https://pinegrow.com/
-- Sublime Text - http://www.sublimetext.com/
-- Visual Studio Code (free) - https://code.visualstudio.com/
-- Wappler ~ Visual Web App Builder - https://wappler.io/
============
ONLINE SITE BUILDERS:
-- Adobe Behance (free) - https://help.behance.net/hc/articles/204483894-Guide-Intro-to-Behance
-- Adobe Portfolio (free with a paid Creative Cloud Plan) - https://portfolio.adobe.com/

-- Adobe Express ($10/mo for Premium access) https://www.adobe.com/express/spotlight/marketers
-- Squarespace - https://www.squarespace.com/
-- Webflow - https://webflow.com
-- Wix - https://www.wix.com/
-- WordPress (open source) - https://wordpress.org/

Hope that helps.

enable show older apps in your cc desktop app, 

https://helpx.adobe.com/muse/kb/adobe-muse-end-of-service.html