Do I have to install Creative Cloud?

Yes, it's an integral part of your Creative Cloud plan.

The CC Desktop App is an application manager.  It's necessary to log-in to your account, sync app settings & workspaces, verify subscription status, access apps & services, sync to Fonts, Libraries, Adobe Stock assets, receive notifications of available updates, download, install and uninstall apps, and a whole lot more.  Without the CC Desktop App, you might as well not have a Creative Cloud plan.

Make sure your computer meets the minimum CPU & GPU requirements for Creative Cloud and Photoshop. See below.

- https://helpx.adobe.com/creative-cloud/system-requirements.html
- https://helpx.adobe.com/photoshop/system-requirements.html
- https://helpx.adobe.com/photoshop/kb/photoshop-cc-gpu-card-faq.html

Hope that helps.

Thank you very much for your reply. I talked to an agent and now know how to do it.

The reason why I do not want Creative Cloud is that I do not use cloud storage.

I wonder if there is any other benefit.

there is but it's such a pain to do that AND to prevent the cc desktop app from installing in the future, it's not worth it.

but, if you want to try, contact adobe support and request the current installation file.  be prepared to explain why you don't want to take the easy solution via the cc desktop app.

there are 3 ways to contact adobe; chat, phone and twitter:

chat:
use a browser that allows popups and cookies
and click here, https://helpx.adobe.com/contact.html?rghtup=autoOpen
in the chat field (lower right), type AGENT
be patient, it can take quite a while to reach a human.

phone:
https://helpx.adobe.com/contact/phone.html

twitter:
tweet @AdobeCare

p.s. if you're contacted by anyone (via email or private message), it's much more likely to be a scammer than an adobe representative. ie, double check for an employee badge if contacted in the forums and look for an adobe.com domain in the email address if you click reply to an email. then check again and be very suspicious. any other method of contacting (or offering to contact you) is almost certainly a scam, https://community.adobe.com/t5/using-the-community-discussions/staying-safe-in-the-adobe-support-community/td-p/12919684/redirect_from_archived_page/true