Hi,
The user can download Photoshop - it will download the Creative Cloud Desktop App and use this to handle the installation. They then need to sign in with the Adobe ID (or Enterprise/Federated ID if you have an ETLA agreement) that you used when you assigned them the license. This takes the form of their email address.
See Learn how to download your Adobe Creative Cloud apps
If the end user has no admin rights on their machine you can have greater control over the deployment using a tool such as the Creative Cloud Packager to build a package which you can then deploy either manually of via a system like SCCM.